99mTc production was studied with the aid of photoexcitation by a 4 MeV endpoint energy bremsstrahlung from the LINAC of the Institute of Isotopes, Budapest. The intensity of the -flux was monitored by disc-shaped natural indium plates, placed in front of and behind the small cylindrical aluminium holders containing TcO2 samples in a powder form. Isomeric activities were measured through the 140 keV -line by a Ge spectrometer. The integral cross section at 4 MeV was found to be 63.3±7.1 bMeV, which can be considered reasonable compared to the corresponding value of 55.3 bMeV established for the115In (,)115mIn reaction. We also attempted the photoexcitation of99mTc by irradiation with -rays from a 1.5×1015 Bq60Co source, but no isomeric activity could be observed. This places the first activation level between 1.33 and 4 MeV.