diff --git a/CHANGELOG.md b/CHANGELOG.md
index fa83b972..77a1d1f9 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -5,6 +5,7 @@ This project adheres to [Semantic Versioning](https://semver.org/).
 
 ## [3.0.3.dev0](https://github.com/httpie/httpie/compare/3.0.2...HEAD) (Unreleased)
 
+- Added support for specifying certificate private key passphrases through `--cert-key-pass` and prompts. ([#946](https://github.com/httpie/httpie/issues/946))
 - Fixed escaping of integer indexes with multiple backslashes in the nested JSON builder. ([#1285](https://github.com/httpie/httpie/issues/1285))
 - Fixed displaying of status code without a status message on non-`auto` themes. ([#1300](https://github.com/httpie/httpie/issues/1300))
 - Fixed redundant issuance of stdin detection warnings on some rare cases due to underlying implementation. ([#1303](https://github.com/httpie/httpie/pull/1303))
diff --git a/docs/README.md b/docs/README.md
index b5d139aa..00aff4b8 100644
--- a/docs/README.md
+++ b/docs/README.md
@@ -1489,6 +1489,21 @@ path of the key file with `--cert-key`:
 $ http --cert=client.crt --cert-key=client.key https://example.org
 ```
 
+If the given private key requires a passphrase, HTTPie will automatically detect it
+and ask it through a prompt:
+
+```bash
+$ http --cert=client.pem --cert-key=client.key https://example.org
+http: passphrase for client.key: ****
+```
+
+If you don't want to see a prompt, you can supply the passphrase with the `--cert-key-pass`
+argument:
+
+```bash
+$ http --cert=client.pem --cert-key=client.key --cert-key-pass=my_password https://example.org
+```
+
 ### SSL version
 
 Use the `--ssl=<PROTOCOL>` option to specify the desired protocol version to use.
diff --git a/httpie/cli/argparser.py b/httpie/cli/argparser.py
index b1ab8de1..f9d6674b 100644
--- a/httpie/cli/argparser.py
+++ b/httpie/cli/argparser.py
@@ -10,7 +10,8 @@ from urllib.parse import urlsplit
 from requests.utils import get_netrc_auth
 
 from .argtypes import (
-    AuthCredentials, KeyValueArgType, PARSED_DEFAULT_FORMAT_OPTIONS,
+    AuthCredentials, SSLCredentials, KeyValueArgType,
+    PARSED_DEFAULT_FORMAT_OPTIONS,
     parse_auth,
     parse_format_options,
 )
@@ -148,6 +149,7 @@ class HTTPieArgumentParser(BaseHTTPieArgumentParser):
         self._parse_items()
         self._process_url()
         self._process_auth()
+        self._process_ssl_cert()
 
         if self.args.raw is not None:
             self._body_from_input(self.args.raw)
@@ -236,6 +238,19 @@ class HTTPieArgumentParser(BaseHTTPieArgumentParser):
                 self.env.stdout = self.env.devnull
             self.env.apply_warnings_filter()
 
+    def _process_ssl_cert(self):
+        from httpie.ssl_ import _is_key_file_encrypted
+
+        if self.args.cert_key_pass is None:
+            self.args.cert_key_pass = SSLCredentials(None)
+
+        if (
+            self.args.cert_key is not None
+            and self.args.cert_key_pass.value is None
+            and _is_key_file_encrypted(self.args.cert_key)
+        ):
+            self.args.cert_key_pass.prompt_password(self.args.cert_key)
+
     def _process_auth(self):
         # TODO: refactor & simplify this method.
         self.args.auth_plugin = None
diff --git a/httpie/cli/argtypes.py b/httpie/cli/argtypes.py
index 7bc487ea..8f19c3c5 100644
--- a/httpie/cli/argtypes.py
+++ b/httpie/cli/argtypes.py
@@ -130,16 +130,11 @@ class KeyValueArgType:
         return tokens
 
 
-class AuthCredentials(KeyValueArg):
-    """Represents parsed credentials."""
-
-    def has_password(self) -> bool:
-        return self.value is not None
-
-    def prompt_password(self, host: str):
-        prompt_text = f'http: password for {self.key}@{host}: '
+class PromptMixin:
+    def _prompt_password(self, prompt: str) -> str:
+        prompt_text = f'http: {prompt}: '
         try:
-            self.value = self._getpass(prompt_text)
+            return self._getpass(prompt_text)
         except (EOFError, KeyboardInterrupt):
             sys.stderr.write('\n')
             sys.exit(0)
@@ -150,6 +145,26 @@ class AuthCredentials(KeyValueArg):
         return getpass.getpass(str(prompt))
 
 
+class SSLCredentials(PromptMixin):
+    """Represents the passphrase for the certificate's key."""
+
+    def __init__(self, value: Optional[str]) -> None:
+        self.value = value
+
+    def prompt_password(self, key_file: str) -> None:
+        self.value = self._prompt_password(f'passphrase for {key_file}')
+
+
+class AuthCredentials(KeyValueArg, PromptMixin):
+    """Represents parsed credentials."""
+
+    def has_password(self) -> bool:
+        return self.value is not None
+
+    def prompt_password(self, host: str) -> None:
+        self.value = self._prompt_password(f'password for {self.key}@{host}:')
+
+
 class AuthCredentialsArgType(KeyValueArgType):
     """A key-value arg type that parses credentials."""
 
diff --git a/httpie/cli/definition.py b/httpie/cli/definition.py
index 5ccc3a16..0a0efafa 100644
--- a/httpie/cli/definition.py
+++ b/httpie/cli/definition.py
@@ -8,7 +8,7 @@ from textwrap import dedent, wrap
 from .. import __doc__, __version__
 from .argparser import HTTPieArgumentParser
 from .argtypes import (
-    KeyValueArgType, SessionNameValidator,
+    KeyValueArgType, SessionNameValidator, SSLCredentials,
     readable_file_arg, response_charset_type, response_mime_type,
 )
 from .constants import (
@@ -803,6 +803,17 @@ ssl.add_argument(
     '''
 )
 
+ssl.add_argument(
+    '--cert-key-pass',
+    default=None,
+    type=SSLCredentials,
+    help='''
+    The passphrase to be used to with the given private key. Only needed if --cert-key
+    is given and the key file requires a passphrase.
+
+    '''
+)
+
 #######################################################################
 # Troubleshooting
 #######################################################################
diff --git a/httpie/client.py b/httpie/client.py
index 06235d24..1984537c 100644
--- a/httpie/client.py
+++ b/httpie/client.py
@@ -19,7 +19,7 @@ from .encoding import UTF8
 from .models import RequestsMessage
 from .plugins.registry import plugin_manager
 from .sessions import get_httpie_session
-from .ssl_ import AVAILABLE_SSL_VERSION_ARG_MAPPING, HTTPieHTTPSAdapter
+from .ssl_ import AVAILABLE_SSL_VERSION_ARG_MAPPING, HTTPieCertificate, HTTPieHTTPSAdapter
 from .uploads import (
     compress_request, prepare_request_body,
     get_multipart_data_and_content_type,
@@ -262,7 +262,14 @@ def make_send_kwargs_mergeable_from_env(args: argparse.Namespace) -> dict:
     if args.cert:
         cert = args.cert
         if args.cert_key:
-            cert = cert, args.cert_key
+            # Having a client certificate key passphrase is not supported
+            # by requests. So we are using our own transportation structure
+            # which is compatible with their format (a tuple of minimum two
+            # items).
+            #
+            # See: https://github.com/psf/requests/issues/2519
+            cert = HTTPieCertificate(cert, args.cert_key, args.cert_key_pass.value)
+
     return {
         'proxies': {p.key: p.value for p in args.proxy},
         'stream': True,
diff --git a/httpie/ssl_.py b/httpie/ssl_.py
index cdec18f8..b9438543 100644
--- a/httpie/ssl_.py
+++ b/httpie/ssl_.py
@@ -1,4 +1,5 @@
 import ssl
+from typing import NamedTuple, Optional
 
 from httpie.adapters import HTTPAdapter
 # noinspection PyPackageRequirements
@@ -24,6 +25,17 @@ AVAILABLE_SSL_VERSION_ARG_MAPPING = {
 }
 
 
+class HTTPieCertificate(NamedTuple):
+    cert_file: Optional[str] = None
+    key_file: Optional[str] = None
+    key_password: Optional[str] = None
+
+    def to_raw_cert(self):
+        """Synthesize a requests-compatible (2-item tuple of cert and key file)
+        object from HTTPie's internal representation of a certificate."""
+        return (self.cert_file, self.key_file)
+
+
 class HTTPieHTTPSAdapter(HTTPAdapter):
     def __init__(
         self,
@@ -47,6 +59,13 @@ class HTTPieHTTPSAdapter(HTTPAdapter):
         kwargs['ssl_context'] = self._ssl_context
         return super().proxy_manager_for(*args, **kwargs)
 
+    def cert_verify(self, conn, url, verify, cert):
+        if isinstance(cert, HTTPieCertificate):
+            conn.key_password = cert.key_password
+            cert = cert.to_raw_cert()
+
+        return super().cert_verify(conn, url, verify, cert)
+
     @staticmethod
     def _create_ssl_context(
         verify: bool,
@@ -61,3 +80,17 @@ class HTTPieHTTPSAdapter(HTTPAdapter):
             # in `super().cert_verify()`.
             cert_reqs=ssl.CERT_REQUIRED if verify else ssl.CERT_NONE
         )
+
+
+def _is_key_file_encrypted(key_file):
+    """Detects if a key file is encrypted or not.
+
+    Copy of the internal urllib function (urllib3.util.ssl_)"""
+
+    with open(key_file, "r") as f:
+        for line in f:
+            # Look for Proc-Type: 4,ENCRYPTED
+            if "ENCRYPTED" in line:
+                return True
+
+    return False
diff --git a/tests/client_certs/password_protected/client.key b/tests/client_certs/password_protected/client.key
new file mode 100644
index 00000000..1634352f
--- /dev/null
+++ b/tests/client_certs/password_protected/client.key
@@ -0,0 +1,42 @@
+-----BEGIN RSA PRIVATE KEY-----
+Proc-Type: 4,ENCRYPTED
+DEK-Info: AES-128-CBC,93DA845817852FB576163AA829C232E9
+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-----END RSA PRIVATE KEY-----
diff --git a/tests/client_certs/password_protected/client.pem b/tests/client_certs/password_protected/client.pem
new file mode 100644
index 00000000..08ee6522
--- /dev/null
+++ b/tests/client_certs/password_protected/client.pem
@@ -0,0 +1,26 @@
+-----BEGIN CERTIFICATE-----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+-----END CERTIFICATE-----
diff --git a/tests/test_ssl.py b/tests/test_ssl.py
index f930bf28..fc587064 100644
--- a/tests/test_ssl.py
+++ b/tests/test_ssl.py
@@ -6,6 +6,8 @@ import pytest_httpbin.certs
 import requests.exceptions
 import urllib3
 
+from unittest import mock
+
 from httpie.ssl_ import AVAILABLE_SSL_VERSION_ARG_MAPPING, DEFAULT_SSL_CIPHERS
 from httpie.status import ExitStatus
 
@@ -32,6 +34,15 @@ CLIENT_CERT = str(CERTS_ROOT / 'client.crt')
 CLIENT_KEY = str(CERTS_ROOT / 'client.key')
 CLIENT_PEM = str(CERTS_ROOT / 'client.pem')
 
+# In case of a regeneration, use the following commands
+# in the PWD_TESTS_ROOT:
+#   $ openssl genrsa -aes128 -passout pass:password 3072 > client.pem
+#   $ openssl req -new -x509 -nodes -days 10000 -key client.pem > client.pem
+PWD_TESTS_ROOT = CERTS_ROOT / 'password_protected'
+PWD_CLIENT_PEM = str(PWD_TESTS_ROOT / 'client.pem')
+PWD_CLIENT_KEY = str(PWD_TESTS_ROOT / 'client.key')
+PWD_CLIENT_PASS = 'password'
+PWD_CLIENT_INVALID_PASS = PWD_CLIENT_PASS + 'invalid'
 
 # We test against a local httpbin instance which uses a self-signed cert.
 # Requests without --verify=<CA_BUNDLE> will fail with a verification error.
@@ -165,3 +176,37 @@ def test_pyopenssl_presence():
     else:
         assert urllib3.util.ssl_.IS_PYOPENSSL
         assert urllib3.util.IS_PYOPENSSL
+
+
+@mock.patch('httpie.cli.argtypes.SSLCredentials._prompt_password',
+            new=lambda self, prompt: PWD_CLIENT_PASS)
+def test_password_protected_cert_prompt(httpbin_secure):
+    r = http(httpbin_secure + '/get',
+             '--cert', PWD_CLIENT_PEM,
+             '--cert-key', PWD_CLIENT_KEY)
+    assert HTTP_OK in r
+
+
+@mock.patch('httpie.cli.argtypes.SSLCredentials._prompt_password',
+            new=lambda self, prompt: PWD_CLIENT_INVALID_PASS)
+def test_password_protected_cert_prompt_invalid(httpbin_secure):
+    with pytest.raises(ssl_errors):
+        http(httpbin_secure + '/get',
+             '--cert', PWD_CLIENT_PEM,
+             '--cert-key', PWD_CLIENT_KEY)
+
+
+def test_password_protected_cert_cli_arg(httpbin_secure):
+    r = http(httpbin_secure + '/get',
+             '--cert', PWD_CLIENT_PEM,
+             '--cert-key', PWD_CLIENT_KEY,
+             '--cert-key-pass', PWD_CLIENT_PASS)
+    assert HTTP_OK in r
+
+
+def test_password_protected_cert_cli_arg_invalid(httpbin_secure):
+    with pytest.raises(ssl_errors):
+        http(httpbin_secure + '/get',
+             '--cert', PWD_CLIENT_PEM,
+             '--cert-key', PWD_CLIENT_KEY,
+             '--cert-key-pass', PWD_CLIENT_INVALID_PASS)