The present work is a continuation of a study of the influence of geometric characteristics on the performance of reverse-flow cylindrical-conical cyclones. After studying the behavior of the pressure drop in previous work (Arnosti et al., 1998), here performance in terms of collection efficiency in the removal of particulate material is addressed. The independent variables considered in this study were inlet gas velocity (three velocities) and the following dimensions of the cyclone: the cylindrical section (three heights) and internal height of the gas exit duct (three heights). The tests were performed using an 33 experimental design. Analysis of the results for overall efficiency was carried out using response surfaces and the statistical parameters were estimated from linear regression.