Photo- and electron-sensitivities of K₂ [Cu (C₂O₄) ₂]·2H₂O and CuC₂O₄·1/2H₂O were studied by measuring the variation of reflection density upon radiation with ultraviolet light and electron beam. K₂ [Cu (C₂O₄) ₂]·2H₂O is thermally developable. Its photographic sensitivities which were measured as radiation energy required to obtain D =0.1 above fog, are 2.2×10⁶erg/cm² at 254 nm and 1.6×10⁷erg/cm² at 334 nm after development. Electron sensitivities measured in the same way are 3.5×10^-7 and 2.4×10^-6 C/cm² for K₂ [Cu (C₂O₄) ₂]·2H₂O after development and CuC₂O₄·1/2H₂O, respectively. The influence of several binders on the photographic sensitivity of CuC₂O₄·1/2H₂O was studied for both ultraviolet light and electron beam radiations. The sensitivity was found to be inversely proportional to the permeability of oxygen into binder film. Cu₂O was found to be one of the photolysis products of either of the two compounds.