The values of H/=and S/=could be determined from the plot of ln (km/Tm) vs. 1/Tmas extrapolated slope and intercept, respectively.The calculated thermokinetic parameters related to thermal inter-conversion reaction of nitro and nitrito pentaamminecobalt(III)complexes are summarized in Tables 3 and 4. The data show that the rate of inter conversion of Cl−and Br−salts of both nitro and nitritoisomers are more than that of I−and PF6−. In agreement with some crystal lographic results [13,16], this difference can be attributed to different volume changes of different salts that occur during linkage isomerization, so that the salts of I−and PF6−ions showmore pronounced crystal structure change compared to that of Cl