Airlift reactor concept was used for hydrogen sulfide removal from acid gases using chelated iron solution. Rate equations for absorption and regeneration reactions were determined and finally, an 'Autosweet' program was developed for design and simulation of the reactor. Variations of the concentration profiles of the reactants and products with time, the required time to achieve steady state conditions, concentration profiles of two phases at steady state and volume of the reactor in absorption and regeneration sections can be calculated based on implemented model in this study. Comparison of theoretical and experimental results shows a good agreement and justifies the model. Based on the model as a second stage of project, a 1 m(3) prototype reactor was designed and constructed at NIOC Research Institute of Petroleum Industry. Crown Copyright (C) 2009 Published by Elsevier B.V. on behalf of The Institution of Chemical Engineers. All rights reserved.