The imidazole catalysed hydrolysis of triacetin reaction is being used as a standard test method for isothermal microcalorimeters where the reaction parameters, rate constant and enthalpy change are used as the reaction specification. To increase the robustness of the test method and to expand on our intellectual enquiry for the study of reactions by calorimetry, this paper improves upon the previous mathematical model for the reaction. Our findings are that the rate constant determined from the model used in previous studies has a linear dependency on the reciprocal concentration of triacetin. To account for this dependence on triacetin and for the dependence on imidazol, demonstrated by others using the same model, this paper presents a more general mathematical model that can be used to obtain reaction parameters in a broader context. At a fixed concentration of imidazol, a triacetin independent rate constant was determined as 1.91 x 10(-7) +/- 1.68 x 10(-8) dm(3) mol(-1) s(-1). (C) 2004 Elsevier B.V. All rights reserved.