The real part of the dielectric constant, K′, has been measured for high-resistivity films of CdSe at temperatures between 4.2 and 240 °K, at frequencies between 500 Hz and 50 kHz. Typically, its value is 9.0 at 4.2 °K, 9.5 at 77 °K, and it increases slowly with temperature to 10.0 at 240 °K. Within experimental error it is independent of frequency in the above range.The electrical resistivity of vacuum-deposited CdSe films has been investigated to determine the effect of substrate temperature, deposition rate, film thickness, sample aging, and heat treating. Measurements of film resistivity variations with temperature from 125 to 350 °K reveals the presence of two activation energies in the lower-resistivity films, but only one in the high-resistivity films in this temperature range.