In this paper a graphical and analytical method is presented for generating reaction isotherms from a set of non-isotherms andvice versa. The method was tested by using computer generated curves. The method was also checked by studying the kinetics of dehydration of calcium oxalate in a static atmosphere. The reaction was monitored in both non-isothermal (with nine heating rates between 0.5 and 60°C min−1) and isothermal modes (at 150, 160 and 170°C). The 160°C isotherm obtained experimentally was compared with that obtained by graphical method from non-isotherms determined experimentally and the differences of α were less than 3%.