This paper describes a new, general-purpose computer code for modeling air pollutants, both in the gas phase and in conjunction with cloud and precipitation systems. The code is based on Eulerian representations of conservation equations for chemical species, energy, and the physical media (e.g. air, cloud water, rain water, ice,…) in which the chemical species reside. Because energy and moisture conservation equations are included, the code is capable of simulating cloud and storm formation, and can deal directly with the attachment, wet-chemistry and deposition processes associated with precipitating systems. The code has been structured to allow considerable flexibility in its use. One-, two- or three-dimensional simulations can be performed, and selection of modeled chemical species, physical media, physicochemical interaction mechanisms, spatial/temporal domain and grid spacing is at the option of the user. A simple example simulation, corresponding to the scavenging of sulfur and nitrogen oxides in a frontal storm system, is presented to illustrate the code's use.