MATSAS is a script-based MATLAB® program for analysis of small angle scattering (SAS) of neutrons and X-rays data obtained from various facilities. The program has primarily been developed for sedimentary rock samples but is equally applicable for other porous media. MATSAS imports raw SAS data from Excel spreadsheets or CSV files, combines small angle scattering and very small angle scattering data, subtracts the background signals, and displays the processed scattering curves in log–log plots. MATSAS uses the polydisperse spherical (PDSP) model to obtain structural information of scatterers (scattering objects); for a porous system, results include specific surface area, porosity, and differential and logarithmic differential pore area/volume distributions. In addition, pore and surface fractal dimensions are obtained from the scattering profiles. The program package allows simultaneous and rapid analysis of a batch of samples (countless); results are then exported to XLSX and CSV files for individual samples. MATSAS is the first SAS program that delivers a full suite of pore characterisations for sedimentary rocks. MATSAS is an open-source package, which is freely available at GitHub (here); the preprint of its manuscript is provided as well. We welcome contributions from the SAS community, including comments, bug fixes, and source code contributions. Feedback can be sent to the GitHub’s forums.