Abstract. A first comparison of the standards for air kerma of the Instituto Tecnológico e Nuclear (ITN), Portugal and of the Bureau International des Poids et Mesures (BIPM) has been carried out in ⁶⁰Co radiation under the auspices of the key comparison BIPM.RI(I)-K1. The comparison result, expressed as a ratio of the ITN standard and the BIPM standard, is 1.0015 (0.0018). The degrees of equivalence between the ITN and the other participants in the key comparison have been calculated and the results are presented in the form of a matrix. A graphical presentation is also given.

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The final report has been peer-reviewed and approved for publication by the CCRI Section I, according to the provisions of the CIPM Mutual Recognition Arrangement (MRA).