Perceptual illusions enable designers to go beyond hardware limitations to create rich haptic content. Nevertheless, spatio-temporal interactions for thermal displays have not been studied thoroughly. We focus on the apparent motion of hot and cold thermal pulses delivered at the thenar eminence of both hands. Here we show that 1000 ms hot and cold thermal pulses overlapping for about 40% of their actuation time are likely to produce a continuous apparent motion sensation. Furthermore, we show that the quality of the illusion (defined as the motion's temporal continuity) was more sensitive to changes in SOA for cold pulses in relation to hot pulses.