Infrared (IR) thermography enabled by a small camera attached to a mobile phone is used in the present research for the determination of the heating dynamics of biological liquid samples exposed to 2.3 GHz continuous wave. The methodology is presented and analysed and some relevant examples are Figured out. Differences in electromagnetic field dissipation are nicely emphasized proving that microwaves dosimetry applied to surfaces, if enough resolution and frame frequency is enabled, may represent a valuable tool in observing heating dynamics of the exposed surfaces even at the microscale.