Abstract: A comparison has been made between the sensitometric results obtained from sulphur-sensitized cubic silver bromide emulsions which are latensified and hypersensitized with a gold thiocyanate solution, respectively, and those obtained from sulphur-plus-gold sensitized emulsions. An increase in the speed of sulphur-sensitized emulsion by gold latensification demonstrates the enhancing action of gold on the development of emulsion grains. On the other hand, the effect of sulphur-sensitization plus gold latensification is less pronounced than that of sulphur-plus-gold sensitization, whereas, the effect of sulphur-sensitization plus gold hypersensitization is more pronounced than that of sulphur-plus-gold sensitization. This implies some functions of gold in enhancing latent image formation during exposure.The ionic conductivity of these emulsions are measured by the Dember effect. Kinetic analysis of the signal decay rates shows that there is a decreasing trend in the ionic conductivity of the sulphur-plus-gold sensitized emulsion grains and pseudo-first-order decay parameter as compared with those of the sulphur-sensitized emulsion grains. However, gold hypersensitization obviously decreases the ionic conductivity of the sulphur-sensitized emulsion grains and the pseudo-first-order decay parameter. This supports the view that the hypersensitizing effect arises from the increase in the concentration of silver ions in the grain environmen