Photothermal technique for light microscopy is reported as the new tool for quantitative analysis of single living cell structural and functional properties. Probe laser illumination with phase contrast method allows to visualize thermal field being induced in cell due to absorption of pump laser radiation. In our set up the cell is pumped by the pulsed laser at 532 nm, 10 ns, 0.01-0.4 mJ. The source of probe beam is a pulsed dye laser which forms cell image. Fully automated image cytometer with acquisition rate 1cell/s is described. An acquired cell image is considered as spatially and temporally resolved cell response to non- specific load being induced with a pump laser. Thus we introduce photothermal image cytometry which may be applied for investigation of mechanisms of photodamage, single cell dosimetry, cell functions and structure and thermal phenomena at cell level.