An online database, FATE, has been developed for the interactive retrieval of kinetic and equilibrium constants that are needed for assessing the fate of chemicals in the environment. The database contains values for up to 12 parameters for each chemical. As of December 1991, FATE contained values for about 200 chemicals. FATE is unique in that experimental data are extracted only from primary references. Pertinent experimental conditions are included in the database to support the credibility and applicability of a value. Transformation products are included when they are available. A new computer program is used to extrapolate measured hydrolysis rate constant data to a standard format. Acidic, basic, and neutral contributions are combined to calculate the overall hydrolysis rate constant, and the half-life of the chemical at 25 deg C and pH 7. The data are reported as second-order acidic and basic rates and a first-order neutral rate at 25 deg C. A new computerized expert system will be applied to compute fate constant values that are more reliable than many measured values. The expert system has the capability of crossing chemical boundaries to cover all organic compounds. (Copyright (c) 1993 American Chemical Society.)