Five N-methylpicolinium derivatives were investigated to test their abilities to function as second coinitiators in free radical photopolymerization initiated by N,N'-diethylcarbocyanine-n-butyltriphenylborate photoredox pair (P19B2). As it is shown by the kinetic data, an addition of picolinium derivatives into P19B2 photo-initiating system visibly increases the efficiency of photoinitiation. The results suggest that the rates of photoinitiation depend on the rate of the picolyl radicals formation. The redox potentials of tested N-methylpicolinium derivatives were measured and the calculation of free energy change for the possible electron transfer reactions between all components of the system (both stable and transient individuals) was performed. The results suggest that cyanine dyes are able to start a specific chain of an electron transfer reactions involving different coinitiators (borate salt and N-alkylpicolinium derivatives), giving as a result one photon-two-radicals photochemical response. (C) 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 576-588, 2009