Lexan polycarbonate and Mylar plastic track detectors exposed to different ions have been obtained from JINR, Dubna, USSR. The bulk etch rate,Vb, and track etch rate,Vt, have been measured for different temperatures. Theoretical equations are used to compute the ranges of different ions in Lexan and Mylar detectors. The maximum etched track lengths of these ions agree with theoretical ranges to better than 2%. The dependence of track etch rate,Vt, and normalized track etch rate,Vt/Vb, on the energy-loss,dE/dx, of different charged particles is shown for different etching temperatures. The experimental results showing the effect of heat treatment on latent tracks before etching are also presented.