The Reactive Plume Model (RPM-II) is a computerized model used primarily for estimating short-term concentrations of primary and secondary pollutants resulting from point-source emissions. Two main features of the model are (1) its chemical kinetic mechanism, which explicitly solves the numerous non-linear chemical reactions associated with NOx, ozone, and hydrocarbon cycles, and (2) the horizontal resolution within the plume, which offers a more realistic treatment of the entrainment process. The user's guide discusses the formulation of RPM-II, the uses of RPM-II, and the necessary and optional input requirements. Several sample data sets and model printouts are included to illustrate the model's flexibility. A complete program listing is also included for the user's convenience.