CATALOGIC is a principally new platform for models targeting environmental fate of chemicals. It affords possibility to develop models for simulation of catabolism and metabolism accounting for logic of enzyme controlled molecular transformations. The approach reflects the grouping of genes in operons in microorganisms or formation of enzyme complexes in higher level organisms. This enzyme organization resulted in a channeling effect which initiates a sequence of predefined molecular transformations used for utilization of a specific chemical - the product of one reaction is transferred to the next active site and prevents the release of unstable intermediates in cell compartment. Based on collected empiric catabolic information several layers of hierarchy are used to control the application of molecular transformations. Each molecular transformation is characterized by its inherent probability of occurrence. These probabilities are used to determine the so called apparent probabilities of occurrence depending on the number and type of simultaneously applied transformations. Inherent probabilities are estimated by making use of a non-linear least squares method on the basis of ready biodegradability tests data such as biochemical oxygen demand (BOD), CO2 production, ultimate half-lives, quantities of metabolites, etc. For user convenience, the platform was designed to supports also the pioneer models CATABOL (not accounting for the metabolic logic, kinetic component, multiendpoint information, etc.).