The analysis of the moisture diffusion inside structural elements is key to assess their time-dependent behaviour and performance, not least in the case of natural materials like wood. Although software exists to solve the moisture transfer problem indirectly, there is a dearth of user-friendly open-source codes tailored to the peculiarities of structural timber. This work presents a Python-based code called OpenMoist developed within a procedural programming framework to perform moisture transfer analysis. The code can handle solid and hollow section geometries, moisture dependent parameters as well as orthotropic diffusion properties typically encountered in wood.