The renovation of eggshell wastage into nanocrystalline CaO by solution combustion method under microwave irradiation is vital process. Microwaves influenced to get high surface area, increase in active sites density with morphological difference than the conventional calcinations method. Accordingly various types of catalysts from egg shells such as CaO-M (microwave combustion), CaO-F (combustion in furnace), CaO-C (calcinations of waste egg shells) were synthesized. The obtained catalyst were characterized using XRD, SEM, TPD-CO2, TGA and BET surface area instruments to know the physico-chemical characteristics. The catalytic evolution of these catalysts showed record activity and recyclability at lower temperature for the glycerol carbonate synthesis under the microwave irradiation method. Under the optimize reaction condition CaO-M showed maximum yield of glycerol carbonate of 94%. Thereby catalytic activity of CaO-M showed better performance when compared with CaO-F, CaO-C and commercially obtained CaO. Better catalytic activity of CaO-M is due to higher surface area with lower particle size and increase in active sites. CaO-C showed decreased in activity due to mask of active sited by CO2. The term active site approach was coined; this concept is to develop the catalysts for the industrial applications. Accordingly, various factors such as surface area, particle size and active sites were compared and correlated with the yield of glycerol carbonate. The distribution of active sites on the each nano particle confirms more activity for CaO-M of 93%. and the r value 0.97 showed better correlation within active site approach influence on the product formation.