Following the expression of the need for an americium (Am) standard and particularly for one with a certified americium 243 (243Am) content in 2009 and thereafter by the International Atomic Energy Agency, the Commissariat a l'Energie Atomique (CEA) et aux Energies Alternatives/ Direction de l'Energie Nucleaire of Marcoule and the Joint Research Center in Geel carried out a collaborative project for the production of a certified reference material enriched in 243Am. CEA's Commission d'ETAblissement des Methodes d'Analyse organized an interlaboratory comparison on this material prior to the issuing of its certificate. The usefulness of an interlaboratory comparison to assess the measurement capabilities in the field and to confirm the provisional certified values for the amount contents of 243Am, 241Am, total Am, the isotopic composition and the molar mass of Am has been demonstrated. Further this interlaboratory comparison enabled to derive an indicative value for the n(242mAm)/n(243Am) isotope amount ratio.