diff --git a/scripts/configs/hpl/discrete/gym.yaml b/scripts/configs/hpl/discrete/gym.yaml
index a9fcf1d..80f77d8 100644
--- a/scripts/configs/hpl/discrete/gym.yaml
+++ b/scripts/configs/hpl/discrete/gym.yaml
@@ -16,7 +16,9 @@ algorithm:
   reg_coef: 0.0
   discrete: true
   discrete_group: 8
-  stoc_encoding: false  # for hopper-medium-expert, try true
+  gumbel_softmax: true
+  temperature: 1.0
+  stoc_encoding: false  # for hopper-medium-replay, try true
   rm_label: true
 
 checkpoint: null
@@ -29,7 +31,7 @@ wandb:
   entity: null
   project: null
 
-env: hopper-medium-expert-v2
+env: hopper-medium-replay-v2
 env_kwargs:
 env_wrapper:
 env_wrapper_kwargs:
@@ -79,17 +81,17 @@ network:
 
 rm_dataset:
   - class: D4RLOfflineDataset
-    env: hopper-medium-expert-v2
+    env: hopper-medium-replay-v2
     batch_size: 64 # [64, 128]
     mode: trajectory
     segment_length: 100
     padding_mode: none
   - class: IPLComparisonOfflineDataset
-    env: hopper-medium-expert-v2
+    env: hopper-medium-replay-v2
     batch_size: 8
     mode: human
   - class: D4RLOfflineDataset
-    env: hopper-medium-expert-v2
+    env: hopper-medium-replay-v2
     batch_size: 512
     mode: transition
 rm_dataloader:
@@ -98,7 +100,7 @@ rm_dataloader:
 
 rl_dataset:
   - class: D4RLOfflineDataset
-    env: hopper-medium-expert-v2
+    env: hopper-medium-replay-v2
     batch_size: 512
     mode: transition
 rl_dataloader:
@@ -118,7 +120,7 @@ rm_eval:
   function: eval_reward_model
   eval_dataset_kwargs:
     class: IPLComparisonOfflineDataset
-    env: hopper-medium-expert-v2
+    env: hopper-medium-replay-v2
     batch_size: 32
     mode: human
     eval: false
diff --git a/scripts/configs/hpl/discrete/metaworld.yaml b/scripts/configs/hpl/discrete/metaworld.yaml
index 3c60ed9..61a678b 100644
--- a/scripts/configs/hpl/discrete/metaworld.yaml
+++ b/scripts/configs/hpl/discrete/metaworld.yaml
@@ -16,6 +16,8 @@ algorithm:
   reg_coef: 0.0001
   discrete: true
   discrete_group: 8
+  gumbel_softmax: true
+  temperature: 1.0
   stoc_encoding: true
   rm_label: true
 
diff --git a/wiserl/algorithm/hpl/hpl.py b/wiserl/algorithm/hpl/hpl.py
index 557efd7..b28828f 100644
--- a/wiserl/algorithm/hpl/hpl.py
+++ b/wiserl/algorithm/hpl/hpl.py
@@ -16,6 +16,7 @@
 from wiserl.module.net.mlp import MLP
 from wiserl.utils.functional import expectile_regression
 from wiserl.utils.misc import make_target, sync_target
+from wiserl.utils.distributions import OneHotCategoricalSTGumbelSoftmax
 
 
 class Decoder(nn.Module):
@@ -70,6 +71,8 @@ def __init__(
         stoc_encoding: bool = True,
         discrete: bool = True,
         discrete_group: int = 8,
+        gumbel_softmax: bool = False,
+        temperature: float = 1.0,
         **kwargs
     ):
         self.expectile = expectile
@@ -89,6 +92,8 @@ def __init__(
         self.stoc_encoding = stoc_encoding
         self.discrete = discrete
         self.discrete_group = discrete_group
+        self.gumbel_softmax = gumbel_softmax
+        self.temperature = temperature
         self.rm_label = rm_label
         super().__init__(*args, **kwargs)
         # define the attention mask for future prediction
@@ -200,10 +205,16 @@ def select_reward(self, batch, deterministic=False):
     def get_z_distribution(self, logits):
         if self.discrete:
             logits = logits.reshape(*logits.shape[:-1], self.discrete_group, -1)
-            return torch.distributions.Independent(
-                torch.distributions.OneHotCategoricalStraightThrough(logits=logits),
-                reinterpreted_batch_ndims=1
-            )
+            if self.gumbel_softmax:
+                return torch.distributions.Independent(
+                    OneHotCategoricalSTGumbelSoftmax(self.temperature, logits=logits),
+                    reinterpreted_batch_ndims=1
+                )
+            else:
+                return torch.distributions.Independent(
+                    torch.distributions.OneHotCategoricalStraightThrough(logits=logits),
+                    reinterpreted_batch_ndims=1
+                )
         else:
             mean, logstd = logits.chunk(2, dim=-1)
             return torch.distributions.Independent(
diff --git a/wiserl/utils/distributions.py b/wiserl/utils/distributions.py
index 141ecad..dea4c41 100644
--- a/wiserl/utils/distributions.py
+++ b/wiserl/utils/distributions.py
@@ -3,8 +3,8 @@
 
 import numpy as np
 import torch
-from torch.distributions import Normal
-
+from torch.distributions import Normal, OneHotCategorical
+from torch.distributions.utils import clamp_probs
 
 class TanhNormal(Normal):
     def __init__(self,
@@ -40,3 +40,32 @@ def entropy(self):
     @property
     def tanh_mean(self):
         return torch.tanh(self.mean)
+
+
+class OneHotCategoricalSTGumbelSoftmax(OneHotCategorical):
+    r"""
+    Creates a reparameterizable :class:`OneHotCategorical` distribution based on the straight-
+    through gumbel-softmax estimator from [1].
+
+    [1] Categorical Reparametrization with Gumbel-Softmax
+    (Jang et al, 2017)
+    """
+    has_rsample = True
+    
+    def __init__(self, temperature, probs=None, logits=None, validate_args=None):
+        super().__init__(probs, logits, validate_args=validate_args)
+        self.temperature = temperature
+    
+    def gumbel_softmax_sample(self, sample_shape=torch.Size()):
+        shape = self._extended_shape(sample_shape)
+        uniforms = clamp_probs(
+            torch.rand(shape, dtype=self.logits.dtype, device=self.logits.device)
+        )
+        gumbels = -((-(uniforms.log())).log())
+        y = self.logits + gumbels
+        return torch.nn.functional.softmax(y / self.temperature, dim=-1)
+
+    def rsample(self, sample_shape=torch.Size()):
+        samples = self.sample(sample_shape)
+        gumbel_softmax_samples = self.gumbel_softmax_sample(sample_shape)
+        return samples + (gumbel_softmax_samples - gumbel_softmax_samples.detach())