A procedure for analyzing the performance of non-isothermal solar reactors for methanol decomposition was developed, based on a model of thermal loss from direct steam generation collector and a comprehensive kinetic model of methanol decomposition employing BASF K3-110 catalyst. It was found that catalytic bed temperature tends towards a certain value, which depends on the chemical reaction type, radiation intensity and collector structure mainly. For a beam incidence angle of 0 degrees, system efficiency increases from 56% at a radiation intensity of 400 W m(-2) to almost 58% at a radiation intensity of 1000 W m(-2). For a radiation intensity of 400 W m(-2), beam incidence angle of 20 degrees, absorber length of 10 m, feed temperature of 373 K and ratio of reaction section of 0.9, the mole flow rate of feed in the range of 0.21-0.23 mol s(-1) results in a maximum quantity of reacted methanol of 0.146 mol s(-1), while a mole flow rate of feed of 0.15 mol s(-1) leads to a maximum system efficiency of 54.2%. The research indicates that the pre-heating section should be as short as possible for effective use of solar energy. (c) 2006 Elsevier Ltd. All rights reserved.