The internal bremsstrahlung (IB) accompanying the first-forbidden unique electron-capture decay of 41Ca has been studied in detail. The IB spectrum measured in coincidence with potassium KX-rays has yielded the probability ratio of the 1s component of IB to the nonradiative K-capture (2.5 ± 0.3) × 10 -4. Singles measurements have been performed to investigate the shape of the IB spectrum, and the results have been compared with the theory of Glauber and Martin for allowed decays and with that of Zon and Rapoport for forbidden transitions. The intensity of the 1s component has been found to be nearly an order of magnitude higher than the theoretical predictions. The shape of the total 1B spectrum closely resembles that of "allowed" character and is thus considerably different from the shape derived from the Zon and Rapoport theory.