The kinetics of MicroRite™ microwave doneness indicator (DI) tags were evaluated at six constant temperatures for six tag widths using the relationship: width2 = k∗time. The rate constant results fit the Arrhenius, In k vs. 1/T, relationship very well (r2 = 0.85). The DI tags performed as predicted by the determined kinetic parameters under variable temperature conditions both external and internal to a microwave oven. Microwave foods with three package designs were cooked at 400 to 1000 W while monitoring internal and surface temperatures. The time/temperature profile of the food was used to determine the DI tag width that would indicate the cook time necessary to insure that a seven log cycle reduction in vegetative pathogen number had occurred.