diff --git a/.github/workflows/builds.yml b/.github/workflows/builds.yml
index c92fe48..46717c5 100644
--- a/.github/workflows/builds.yml
+++ b/.github/workflows/builds.yml
@@ -13,7 +13,7 @@ jobs:
       fail-fast: false
       matrix:
         os: [ubuntu-latest]
-        python: ['3.10']
+        python: ['3.9']
     
     steps:
       - uses: actions/checkout@v4
diff --git a/.github/workflows/doc-status.yml b/.github/workflows/doc-status.yml
index 56c48df..9cbbb8f 100644
--- a/.github/workflows/doc-status.yml
+++ b/.github/workflows/doc-status.yml
@@ -9,7 +9,7 @@ jobs:
       - name: Set up Python
         uses: actions/setup-python@v4
         with:
-          python-version: 3.10
+          python-version: 3.9
           architecture: x64
       - name: check status
         run: |
diff --git a/.github/workflows/docs.yml b/.github/workflows/docs.yml
index 6861e82..17cf720 100644
--- a/.github/workflows/docs.yml
+++ b/.github/workflows/docs.yml
@@ -9,7 +9,7 @@ jobs:
     strategy:
       matrix:
         os: [ubuntu-latest]
-        python: ['3.10']
+        python: ['3.9']
     steps:
       - uses: actions/checkout@v4
         with:
diff --git a/.github/workflows/gh-page.yml b/.github/workflows/gh-page.yml
index bbaf278..3e1636b 100644
--- a/.github/workflows/gh-page.yml
+++ b/.github/workflows/gh-page.yml
@@ -6,10 +6,10 @@ jobs:
   see-page-build-payload:
     runs-on: ubuntu-latest
     steps:
-      - name: Set up Python 3.10
+      - name: Set up Python 3.9
         uses: actions/setup-python@v4
         with:
-          python-version: 3.10
+          python-version: 3.9
           architecture: x64
       - name: check status
         run: |
diff --git a/.github/workflows/release.yml b/.github/workflows/release.yml
index 33da342..ca6d9f1 100644
--- a/.github/workflows/release.yml
+++ b/.github/workflows/release.yml
@@ -13,7 +13,7 @@ jobs:
       - name: Set up Python
         uses: actions/setup-python@v4
         with:
-          python-version: 3.10
+          python-version: 3.9
           architecture: x64
       - name: Cache python modules
         uses: actions/cache@v4
@@ -47,7 +47,7 @@ jobs:
       - name: Set up Python
         uses: actions/setup-python@v4
         with:
-          python-version: 3.10
+          python-version: 3.9
           architecture: x64
       - name: Install package
         run: |
@@ -64,7 +64,7 @@ jobs:
         uses: conda-incubator/setup-miniconda@v4
         with:
           auto-update-conda: true
-          python-version: 3.10
+          python-version: 3.9
       - name: Install dependencies
         run: |
           conda install -y conda-build conda-verify anaconda-client
@@ -90,7 +90,7 @@ jobs:
     strategy:
       matrix:
         os: [ubuntu-latest, macos-latest, windows-latest]
-        python: ['3.10']
+        python: ['3.9']
     steps:
       - uses: actions/checkout@v4
       - name: Miniconda setup
diff --git a/.github/workflows/style.yml b/.github/workflows/style.yml
index f11bb52..1c86ccc 100644
--- a/.github/workflows/style.yml
+++ b/.github/workflows/style.yml
@@ -12,7 +12,7 @@ jobs:
     strategy:
       matrix:
         os: [ubuntu-latest]
-        python: ['3.10']
+        python: ['3.9']
     steps:
       - uses: actions/checkout@v4
       - name: Set up Python
@@ -31,7 +31,7 @@ jobs:
     strategy:
       matrix:
         os: [ubuntu-latest]
-        python: ['3.10']
+        python: ['3.9']
     steps:
       - uses: actions/checkout@v4
       - name: Set up Python
@@ -51,7 +51,7 @@ jobs:
     strategy:
       matrix:
         os: [ubuntu-latest]
-        python: ['3.10']
+        python: ['3.9']
     steps:
       - uses: actions/checkout@v4
       - name: Set up Python
@@ -79,7 +79,7 @@ jobs:
     strategy:
       matrix:
         os: [ubuntu-latest]
-        python: ['3.10']
+        python: ['3.9']
     steps:
       - uses: actions/checkout@v4
       - name: Set up Python
@@ -98,7 +98,7 @@ jobs:
     strategy:
       matrix:
         os: [ubuntu-latest]
-        python: ['3.10']
+        python: ['3.9']
     steps:
       - uses: actions/checkout@v4
       - name: Set up Python
diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index 1b170f5..c8f6a7a 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -12,7 +12,7 @@ jobs:
     strategy:
       matrix:
         os: [ubuntu-latest]
-        python: ['3.10']
+        python: ['3.9']
     steps:
       - uses: actions/checkout@v4
         with:
@@ -67,7 +67,7 @@ jobs:
     strategy:
       matrix:
         os: [ubuntu-latest]
-        python: ['3.10']
+        python: ['3.9']
     steps:
       - uses: actions/checkout@v4
         with:
diff --git a/README.md b/README.md
index 134c415..ca31dac 100644
--- a/README.md
+++ b/README.md
@@ -52,7 +52,7 @@ prediction = engine.predict(im)
 
 ## Setup
 
-Python 3.10 (or higher) and [pip](https://pip.pypa.io/en/stable/)/[conda](https://docs.conda.io/en/latest/miniconda.html) are required to install PyroEngine.
+Python 3.9 (or higher) and [pip](https://pip.pypa.io/en/stable/)/[conda](https://docs.conda.io/en/latest/miniconda.html) are required to install PyroEngine.
 
 ### Developer installation
 
diff --git a/pyproject.toml b/pyproject.toml
index 98ece70..ff9e505 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -20,9 +20,9 @@ classifiers = [
     "Natural Language :: English",
     "Operating System :: OS Independent",
     "Programming Language :: Python :: 3",
-    "Programming Language :: Python :: 3.10",
     "Programming Language :: Python :: 3.9",
-    "Programming Language :: Python :: 3.10",
+    "Programming Language :: Python :: 3.9",
+    "Programming Language :: Python :: 3.9",
     "Programming Language :: Python :: 3.11",
     "Topic :: Scientific/Engineering",
     "Topic :: Scientific/Engineering :: Mathematics",