Cadmium selenide, CdSe, nano particles have been synthesized in aqueous solution containing equimolar ammoniated CdSO₄ and Na₂SeSO₃ as the starting materials without any capping agents, using gamma and electron beam irradiation under a reducing condition. The radiolytic processes occurring in water result in the formation of CdSe nano particles through there actions mediated by hydrated electrons, e_aq^_. TEM measurements revealed that the CdSe nano particles were found to exist in agglomerates of dimension of about 100 nm, consisting of primary nano particles of dimensions within 5 nm. The as-grown nano particles were of cubic crystalline phase as supported by the XRD measurements. These bare CdSe nano particles exhibit room temperature ferromagnetic (RTFM) behavior. However, the RTFM behavior was found to be 30% higher in the case of CdSe nano particles prepared on electron beam irradiation as compared to those obtained by gamma irradiation, which was attributed to their relatively smaller size(2–3nm)and disordered structures as compared to those obtained in the later case(3–5 nm).