A first intense investigation in the kinetics of radical polymerization of NVP was done by Senogles et. al. [7] They revealed a variation of the activation energy for the propagation step Radical PolymerizationAn improved kinetic model for the radical polymerization of N-vinyl-pyrrolidone (NVP) in aqueous medium is developed. Quantum chemical simulations reveal that the transfer to polymer is of minor importance whereas the transfer to monomer by hydrogen abstraction in 3-position of the pyrrolidone ring leads to a radical with a double bond which initiates a new chain bearing a terminal double bond (TDB). The resulting dead chains with one, two, or more TDB are the main source for a strong increase of molar mass in batch reactors at high conversion due to long chain branching and crosslinking. This can be a source for gel formation and fouling in continuous reactors. www.advancedsciencenews.com www.mre-journal.de