This paper presents a design procedure for a dual solar/gas-fired generator of an absorption chiller: The solar energy is the primary driving source for the generator, while the natural gas serves as the backup heat when the solar energy is unavailable or insufficient. Saturated forced convective boiling for binary mixtures has been considered to account for the reduction in the heat transfer coefficient observed for most mixtures. The simultaneous solar and gas-fired desorption process was investigated. The generator constructed based on modeling results yielded goon performance in the experiment. [S0195-0738(00)00704-4].