[en] Characterization of a walk-in ²²²Rn calibration chamber installed at the Centre for Advanced Research in Environmental Radioactivity (CARER), Mangalore University for its spatial uniformity of ²²²Rn concentration is taken up using passive, CR-39 based Raduet detectors. The detectors were exposed by placing at various positions in the chamber with a maximum spatial resolution of 0.1 m, 0.07 m and 0.09 m in the x,y,z direction respectively, in a semi dynamic mode of chamber operation. The detectors were exposed for a mean ²²²Rn concentrations of 201 ± 1688 Ba.m^-3 and 5220 ± 548 Bq.m^-3, at a constant relative humidity (RH) for 60% and temperature (T) of 28 ° in the chamber. A good spatial uniformity in ²²²Rn concentration inside the calibration chamber was observed with coefficient of variation (CV%) for track densities of <13%. (author)