This article describes a procedure for carbon-in-pulp (CIP) simulation based on a dual mass-transfer kinetic approach. The method attempts to overcome the short-comings of frequently used single-rate simulation techniques and at the same time, addresses the mathematical complexities of multirate modeling procedures.Operating parameters for a full-scale CIP plant were utilized to test the new simulation approach. It was found that this simplified approach, based entirely on solution concentration, provided a significant improvement on certain current single-rate expression models.