AbstractA kinetic model is presented that can be used to predict moments of size distribution of polymer species in the system where a tri‐functional monomer with groups of different reactivity (such as glycerol) reacts irreversibly with a bi‐functional monomer with no cycle formation. A Smoluchowski‐like equation is used to follow the time evolution of the size distribution of polymer molecules up to the gel point. The results are confronted with calculations made by using the statistical cascade theory. The two methods of calculations give slightly different results. The reasons for the differences are disc