This paper presents a theoretical investigation of the effect of adsorption/desorption times allocation on the performance of adsorption chillers. The ratio between the duration of adsorption and desorption modes is varied to optimize the system performance. Herein, (f) stands for the ratio between duration of desorption and adsorption modes of the adsorption cooling cycle. Employing a two-bed silica gel/water based adsorption chiller, theoretical results show that the system performance in terms of cooling capacity and COP is improved by reducing the ratio (P. However, percentage of improvement depends on the system design and its operating conditions. It is also found that, for each cycle time, there is an optimal value of (f) that maximizes the system performance. Theoretical results show that for a half cycle time of 350 s, switching time of 35 s and f of 0.8, the system delivers continues cooling using only two sorption reactors and minimizes fluctuations in chilled water outlet temperature. (C) 2013 Elsevier Ltd. All rights reserved.