Measurements were performed for the calibration of an ionization chamber in the secondary standard dosimetry laboratory of IFIN-HH. A 10-liter spherical ionization chamber was calibrated using a 1-literspherical reference standard ionization chamber. The ionization chamber’s response to 137Cs was also evaluated computationally by MCNP and FLUKA Monte Carlo codes. The models of the experimental setup are validated and can be used for further studies, especially in cases where the real experiment is hard or impossible to perform