A model of a condensing bubble based on measurements and visualization is used to describe the collapse process of small and intermediate-size bubbles, and to analyze the thermal resistance of the bubble. The thermal resistance inside and outside a bubble increases with the thickness of the condensate film and of the thermal boundary layer respectively. The ratio of thermal resistance, inside to outside, varies from 0. 01 to 10 in the process of collapse. The local heat fluxes and the heat transfer rates decrease steeply at the initial stages of collapse, and slowly at the final stages of the process.