diff --git a/var/spack/repos/builtin/packages/xolotl/package.py b/var/spack/repos/builtin/packages/xolotl/package.py
new file mode 100644
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+++ b/var/spack/repos/builtin/packages/xolotl/package.py
@@ -0,0 +1,65 @@
+# Copyright Spack Project Developers. See COPYRIGHT file for details.
+#
+# SPDX-License-Identifier: (Apache-2.0 OR MIT)
+
+from spack.package import *
+
+
+class Xolotl(CMakePackage, CudaPackage):
+    """Xolotl is a high-performance computing code using
+    advection-reaction-diffusion (ADR) kinetic rate theory to model the
+    time evolution of the divertor material in next generation tokamaks,
+    like ITER, as well as nuclear fuel in fission reactors."""
+
+    homepage = "https://github.com/ORNL-Fusion/xolotl"
+    url = "https://github.com/ORNL-Fusion/xolotl/archive/refs/tags/v3.1.0.tar.gz"
+    git = "https://github.com/ORNL-Fusion/xolotl.git"
+
+    # notify when the package is updated.
+    maintainers("sblondel", "PhilipFackler")
+
+    license("BSD-3-Clause", checked_by="PhilipFackler")
+
+    version("3.1.0", sha256="68a495ab0c3efb495189f73474d218eb591099b90d52d427ac868b63e8fc2ee8")
+
+    depends_on("cxx", type="build")
+
+    depends_on("mpi")
+    depends_on("boost +log +program_options")
+    depends_on("hdf5 +mpi")
+
+    variant("int64", default=True, description="Use 64-bit indices")
+    variant("openmp", default=False, description="Activates OpenMP backend")
+
+    conflicts("+cuda", when="cuda_arch=none")
+    conflicts("+openmp", when="+cuda", msg="Can't use both OpenMP and CUDA")
+
+    depends_on("petsc ~fortran +kokkos")
+    depends_on("petsc +int64", when="+int64")
+    depends_on("petsc +openmp", when="+openmp")
+
+    depends_on("plsm@2.0.4", when="@3.1.0")
+    depends_on("plsm")
+    depends_on("plsm +int64", when="+int64")
+    depends_on("plsm +openmp", when="+openmp")
+
+    for cuda_arch in CudaPackage.cuda_arch_values:
+        depends_on(f"petsc+cuda cuda_arch={cuda_arch}", when=f"+cuda cuda_arch={cuda_arch}")
+        depends_on(f"plsm+cuda cuda_arch={cuda_arch}", when=f"+cuda cuda_arch={cuda_arch}")
+
+    variant("papi", default=False, description="Activates PAPI perfHandler")
+    depends_on("papi", when="+papi")
+
+    variant("vtkm", default=False, description="Activates VTK-m vizHandler")
+    depends_on("vtk-m", when="+vtkm")
+
+    depends_on("boost +test", type="test")
+
+    def cmake_args(self):
+        args = [self.define("BUILD_TESTING", self.run_tests)]
+
+        spec = self.spec
+        if "+vtk-m" in spec:
+            args.append(self.define("VTKm_DIR", spec["vtk-m"].prefix))
+
+        return args