Abstract: This method describes a simultaneous electrodeposition procedure that is specifically adapted for the source preparation of transuranic elements including Np, Pu, Am and Cm for high resolution alpha spectrometric measurement. The effects of electrolyte concentration, pH of buffer, current density and the plating time on the source quality were examined in order to optimize the conditions and to obtain the maximum yield. The electrodeposition yields of ²³⁷Np, ²³⁸Pu, ²⁴³Am and ²⁴⁴Cm are higher than 96% with the ammonium sulfate concentration of 0.2 mol/L, pH ranging from 2.0 to 2.5, current density at 0.40-0.50 A/cm², and plating time over 60 min. In the light of good reproducibility and robustness of the process, the recommended procedure for rapid simultaneous quantitative electrodeposition of Np, Pu, Am and Cm is suitable to preparing high quality mixed transuranic alpha sources.