An unsteady-state model is proposed to describe the complete dynamic process of a positively pulsed corona discharge nonthermal plasma reactor. Case studies of the NO removal in an atmosphere of nitrogen are conducted with different initial NO concentrations. The electron collision reaction kinetics can be treated with a conventional Arrhenius rate expression. The removal of NO proceeds mainly via destruction by the N and N-2(A). Twenty reactions with eight species can describe the reaction mechanism for NO removal in nitrogen very well. Two different initial conditions were applied to study the two dependent concentration distributions. It is demonstrated that the steady state model is a special case of the unsteady state model. Simulation results show excellent agreement with experimental data. The approach presented in this work is universal and can be applied to other pulsed corona discharge systems. (C) 2012 Elsevier Ltd. All rights reserved.