In a recent paper, Markworth and Glasser [J. Appl. Phys.54, 3508 (1983)] claimed to have generalized the Johnson–Mehl–Avrami [W. A. Johnson and R. F. Mehl, Trans. Am. Inst. Min. Metall. Eng.135, 416 (1939), and M. Avrami, J. Chem. Phys.7, 1103 (1939)] equation for the anisothermal case. It is argued that these authors did in fact use different rate equations for iso‐ and anisothermal kinetics. This procedure could lead to large errors in the kinetic parameters. A correct solution of the problem might be found in Henderson’s paper [J. Non‐Cryst. Solids30, 301 (1979)].