Standardization of 142Pr activity concentration

142Pr (praseodymium-142), a potential radionuclide for brachytherapy, was produced after irradiating high purity natural Pr2O3 powder in a research reactor. The irradiated powder was then dissolved in acids and diluted for measurement. Several radioactivity measurement methods were used in the standardization of 142Pr radionuclide. This work reports the results of standardization of 142Pr with CIEMAT/NIST efficiency tracing method, gamma spectrometry and a calibrated ionization chamber. The activity measured from different standardization methods are compatible with each other within the uncertainty limits. The CIEMAT/NIST efficiency tracing method gives the lowest uncertainty and is a reliable method for the standardization of this radionuclide.