This paper presents the results of an experimental study related to the thermal effects on kaolin clay cyclic mobility. The thermal effects were identified by comparing the experimental results of cyclic triaxial tests performed at high temperature (90 C) with results of the same type of test carried out at ambient temperature (22 C). For the testing, a new temperature-controlled triaxial apparatus, developed by the authors, was employed. Experimental evidence shows that shear cycles on the heated samples induced smaller axial strain and pore-water pressure per cycle in comparison with the unheated samples. In addition, shear-induced pore-water pressure at large strains in the heated sample was slightly lower than in the unheated sample. In other words, the heated samples behaved as if they were denser, which is a result of thermal hardening. These results may be applied in geotechnical and earthquake engineering applications as a soil improvement technique.