Thermal decomposition of methylcyclopropane-carboxylate (MCPC) was studied over the temperature range 682-739k and presuure between 5-50 tburr using static system. Isomerization reaction to give methyl-3-butenoate, methyl-2-butenoate (cis+trans) and methyl-2-propenoate accounted for 95% of the methycyclopropane-carboxylate decomposition   These isomerizations are homogeneous first order, non-radical processes Arrhenius parameters are given in the rate equation:   Ktotal/s-1 = 10.13.7±1.2 exp(-236.9±16.8kj mol-1/RT) k1/s-1+13.3±1.6 exp(-243.6±22.5 kjmole-1/RT ); k2/s-1 1013.7±1.4 exp(-233.8±18.6 kjmole-1/RT); k3/s-1+10 13.9±0.8 exp(-251.3±10.7 kj mole -1/RT)       Error limits quoted are statistically 95% certainly limits. The observed Arrhenius parameters are consisitent with the biradical mechanism. Results from the present study are compared with those for cyclopropane isomerization to propane and it is found that the presence of CH3OC=O group on cyclopropane increases the rate constant for structural isomerization by lowering the activation energy for the reaction by 35 kJ mole-