AbstractThe effect of ultraviolet radiation on the nucleating behaviour of AgI, AgCI, AgI–AgCI–CuI system in pure water has been discussed. Also the effect of irradiated AgI—AgCI—CuI samples in the presence of chlorides of sodium, potassium, and ammonium as well as sulphates of sodium, ammonium, and magnesium has been reported. The UV exposed samples of AgI and AgCI become darkened and their nucleating activity is found to be greatly reduced as the time of exposure is increased. It is found that the exposure of the AgI—AgCI—CuI samples to ultra‐violet radiation does not produce a remarkable effect in nucleation activity, except, the samples becoming dark for longer exp