Trap centers in Tl2GaInS4 single crystals have been investigated by thermoluminescence (TL) measurements in the temperature range of 10-110 K. Curve-fitting method was utilized to evaluate the activation energies (12 and 26 meV) of revealed two trap centers. Thermal cleaning method was applied to the spectra and two overlapping peaks were reduced to one single peak corresponding to deeper trap level. The characteristics of heating rate dependence and trap distribution of the separated peak have been studied using experimental techniques based on various heating rates and various illumination temperatures, respectively. Anomalous heating rate dependence was observed carrying out TL measurements with various heating rate between 0.2 and 1.2 K s(-1). This behavior was explained on the base of a semi-localized transition model. Moreover, increase of activation energy from 27 to 67 meV was revealed for the applied illumination temperature range of 26-36 K.