Physical scaling is an efficient and cost-effective modeling tool to be used in fire safety engineering. Scaling of internal wall temperatures was investigated in room fire tests in three different scales, that is, full scale (1:1), medium scale (1:2), and small scale (1:3.5). The fire sources were either placed at the center or in the corner of the enclosures. The measured time-dependent internal wall temperatures, incident heat fluxes, and gas temperatures in different scales are compared and analyzed. Test results show that the proposed scaling method is able to scale the internal wall temperatures (temperatures inside the walls) and incident heat fluxes well, especially in medium scale.