A continuous-discrete Distributed and Decentralized Switching Kalman Filter (DDSKF) is designed for estimation of spatial profiles in Pressure Swing Adsorption (PSA) processes. The introduced observer is an integral part of the control strategy of hybrid systems in general and PSA systems in particular. A reduced order model is developed based on the mechanistic model of the process. The sensors are optimally located and observability of the process is studied. The proposed observer is used to estimate the spatial profiles of various states of a two-bed, six-step PSA system used for production of pure H-2 from a H-2-CH4 gas mixture. The spatial profiles of the system have been estimated using the proposed observer quite accurately and rapidly based on noise corrupted measured temperature and pressure of a few points in the process. (C) 2016 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.