The control of size and dispersity of particles is a crucial aspect of nanoparticle preparation. In this work we report on the use of microwaves along with appropriate choice of surfactants in the reverse micelle method of preparation of nanoparticles of the doped rare earth manganite Sm0.42Ca0.58MnO3 and compare the results with those obtained from conventional reverse micelle technique. We find that the microwave assisted method enables reducing the reaction time dramatically and results in nanoparticles of much smaller size. We also optimise the selection and combination of surfactants as well as the surfactants to water ratio and find that the use of surfactants CTAB/Heptanol/Octanol in the ratio 1.066 with water enables the preparation of particles of smaller size and minimal polydispersity. The study of such particles is expected to lead to the resolution of the longstanding issue of the nature of the charge order (CO) melting in nanomanganites, namely whether the size induced melting of CO in nanomanganites is complete or some residual short-range CO always persists.