diff --git a/CHANGELOG.md b/CHANGELOG.md
index 4c9d601e4..401515994 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,6 +7,7 @@
 
 ### New Features
 - Add `--eval-env-kwargs` to `train.py` (@Quentin18)
+- Added `ppo_lstm` to hyperparams_opt.py (@technocrat13)
 
 ### Bug fixes
 
diff --git a/rl_zoo3/hyperparams_opt.py b/rl_zoo3/hyperparams_opt.py
index 0bbd701f9..360734cd9 100644
--- a/rl_zoo3/hyperparams_opt.py
+++ b/rl_zoo3/hyperparams_opt.py
@@ -28,7 +28,7 @@ def sample_ppo_params(trial: optuna.Trial) -> Dict[str, Any]:
     gae_lambda = trial.suggest_categorical("gae_lambda", [0.8, 0.9, 0.92, 0.95, 0.98, 0.99, 1.0])
     max_grad_norm = trial.suggest_categorical("max_grad_norm", [0.3, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 2, 5])
     vf_coef = trial.suggest_float("vf_coef", 0, 1)
-    net_arch = trial.suggest_categorical("net_arch", ["small", "medium"])
+    net_arch = trial.suggest_categorical("net_arch", ["tiny", "small", "medium"])
     # Uncomment for gSDE (continuous actions)
     # log_std_init = trial.suggest_float("log_std_init", -4, 1)
     # Uncomment for gSDE (continuous action)
@@ -49,6 +49,7 @@ def sample_ppo_params(trial: optuna.Trial) -> Dict[str, Any]:
     # Independent networks usually work best
     # when not working with images
     net_arch = {
+        "tiny": dict(pi=[64], vf=[64]),
         "small": dict(pi=[64, 64], vf=[64, 64]),
         "medium": dict(pi=[256, 256], vf=[256, 256]),
     }[net_arch]
@@ -76,6 +77,28 @@ def sample_ppo_params(trial: optuna.Trial) -> Dict[str, Any]:
     }
 
 
+def sample_ppo_lstm_params(trial: optuna.Trial) -> Dict[str, Any]:
+    """
+    Sampler for RecurrentPPO hyperparams.
+    uses sample_ppo_params(), this function samples for the policy_kwargs
+    :param trial:
+    :return:
+    """
+    hyperparams = sample_ppo_params(trial)
+
+    enable_critic_lstm = trial.suggest_categorical("enable_critic_lstm", [False, True])
+    lstm_hidden_size = trial.suggest_categorical("lstm_hidden_size", [16, 32, 64, 128, 256, 512])
+
+    hyperparams["policy_kwargs"].update(
+        {
+            "enable_critic_lstm": enable_critic_lstm,
+            "lstm_hidden_size": lstm_hidden_size,
+        }
+    )
+
+    return hyperparams
+
+
 def sample_trpo_params(trial: optuna.Trial) -> Dict[str, Any]:
     """
     Sampler for TRPO hyperparams.
@@ -527,6 +550,7 @@ def sample_ars_params(trial: optuna.Trial) -> Dict[str, Any]:
     "sac": sample_sac_params,
     "tqc": sample_tqc_params,
     "ppo": sample_ppo_params,
+    "ppo_lstm": sample_ppo_lstm_params,
     "td3": sample_td3_params,
     "trpo": sample_trpo_params,
 }
diff --git a/tests/test_hyperparams_opt.py b/tests/test_hyperparams_opt.py
index 1fe82f7d2..c9d5e44c0 100644
--- a/tests/test_hyperparams_opt.py
+++ b/tests/test_hyperparams_opt.py
@@ -33,6 +33,8 @@ def _assert_eq(left, right):
 experiments["tqc-parking-v0"] = ("tqc", "parking-v0")
 # Test for TQC
 experiments["tqc-Pendulum-v1"] = ("tqc", "Pendulum-v1")
+# Test for RecurrentPPO (ppo_lstm)
+experiments["ppo_lstm-CartPoleNoVel-v1"] = ("ppo_lstm", "CartPoleNoVel-v1")
 
 
 @pytest.mark.parametrize("sampler", ["random", "tpe"])