In 2005, the Physikalisch-Technische Bundesanstalt (PTB), Germany submitted a sample of known activity of 222Rn to the International Reference System (SIR). The value of the activity submitted was about 1.1 MBq. This key comparison result joins that of Switzerland in the key comparison database that now contains two results, identifier BIPM.RI(II)-K1.Rn-222. Consequently, the KCRV and the degrees of equivalence have been evaluated. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by Section II of the Consultative Committee for Ionizing Radiation (CCRI(II)), according to the provisions of the CIPM Mutual Recognition Arrangement (MRA).