Efficient heat generation by plasmon-resonant gold nanoparticles, together with their biocompatibility and high specificity of biomolecular recognition, opens new possibilities for applications in biomedical applications. In this work, we present an improved method of monitoring surface temperature changes subjected to external stimulation by dynamic IR thermography. The method is based on the careful analysis of an IR image sequence recorded before, during, and after the stimulation that allows one to select areas with significant temperature variation and evaluate temporal behavior of the surface temperature. The method was applied for the experimental study on the photothermal effect in a gold hydrosol containing hollow gold nanoparticles heated with laser beam. Under these conditions, it was seen that the surface temperature of the gold hydrosol (measured with a FLIR SC655 InfraRed Camera, resolution 640 × 480 pixels) under the laser beam gradually increases and reaches a saturation level. It was shown that the developed method is capable of producing a quantitative analysis of the changes in the surface temperature distribution of the gold hydrosol, as well as characterizing the photothermal properties of the nanoparticles.