The present study is concerned with the application of the pseudo-kinetic rate constant method to high pressure LDPE tubular, reactors. The utilization of multiple monomers is of profound importance to the polymer manufacturing industry since it leads to the production of an unlimited number of polymer types with a wide range of properties. However, by increasing the number of comonomers the kinetic rate expressions describing the appearance/disappearance of the various molar species become fairly complex. In order to simplify the kinetic treatment of the resulting expressions, the pseudo-kinetic rate constant method can be employed, in combination with the method of moments, to model the multicomponent free-radical polymerization of ethylene in a high pressure tubular reactor.