Several methods have been explored to produce gelatin‐free thin‐film plates of superior performance for the detection of positive ions. Of these methods, vacuum deposition of silver halides has been found to be the most flexible system and has been examined in an extended series of tests. Particle size, sensitivity, and shape of the response curve were studied as a function of various experimental parameters, such as evaporation temperature, thickness of layer, substrate temperature, ion energy, developing conditions, and others. The plates obtained by this technique have particle sizes of about 1 &mgr; and yield sensitivities, for 20 keV ions, approaching those of Ilford Q2 plates at 50% blackening. When blackeningBis plotted vs logE(E=exposure in coulombs), the slope of the resulting response curve is considerably steeper than that found for Q2 plates. The thin‐film plates produced have a number of advantages over the commercially available Schumann‐type plates: the background blackening of unexposed areas approaches that of clear glass and has an unusually low noise level; spectral line sharpness is greatly improved; the plates show practically no halation, have good conductivity and excellent vacuum properties; and there are no storage problems.