In the present work the dependence of the bulk etch rate of CR-39 solid state nuclear track detectors (SSNTD) on the concentration C and the temperature Tof the NaOH etching solution has been studied. The superposition and interaction of physical and chemical processes happening during the etching phase is tried to approximate by an Arrhenius-like law which is derived from the chemical reaction kinetics in homogeneous phases. A reasonable reproduction of different experimental data was achieved. By the goodness of the fits some conclusions were drawn on the validity of empirical and plausible functional dependence of the bulk etch rate on concentration and temperature of the etchant. If it was found that if a reasonable accordance appeared when comparing fits from one data set to another, the bulk etch rate can nevertheless not be described well for widely varying C and T ranges by means of the used formula. This leads to the conclusion that more refined models have to be developed when applied to both extreme (low and high) values of temperature and concentration.