In this paper, analysis of an open type flat plate collector for tannery effluent treatment is presented. The effects of parameters like orientation of collector, film thickness, insolation, ambient temperature and relative humidity on the effluent evaporation rate are studied. It is found that the collector facing south at an inclination of 12.68° and having a solution film thickness of 5 mm gives maximum year round performance. The performance of this open type flat plate collector is compared with that of the conventional pond. © 1994.