Synthesis of polyacrylonitrile nanoparticles was carried out under the catalytic effect of ill situ developed Co(II)/EDTA complex with ammonium persulphate as initiator, in the absence of added emulsifier. The microemulsion polymerization was studied at varying concentrations of initiator, monomer, complex and solvent over a temperature range of 30-70 degrees C. The overall activation energy (E-a, 49.79 kJ/mol), energy of dissociation of initiator (E-d, 82.68 kJ/mol), number of micelles (0.163 x 10(18)) and the viscosity average molecular weight of the polymer were computed. The distribution of particle sizes was determined by transmission electron microscopy (TEM). It was found that the oil-in-water polymerization was stabilized by the presence of the COCl2/EDTA in situ complex reducing the particle size into nano order. The average diameters of PAN nano particles, obtained by TEM, were in the range of 50-150 nm at maximum conversion. The experimental particle size was mainly dependent on the concentration of complex and temperature.