The denitridation behaviour of binary iron, cobalt and rehnium nitrides under H 2 /Ar has been investigated. The iron nitride was found to lose over 70 % of its as prepared nitrogen content at 400°C. The cobalt nitride was completely denitrided at 250°C. Rhenium nitride lost close to 90 % of its nitrogen at 350°C. In addition, Co-Re 4 prepared by ammonolyis was investigated, whilst only traces of NH 3 were lost from this material under H 2 /Ar at 400°C, with H 2 /N 2 it proved to be an active ambient pressure ammonia synthesis catalyst in accordance with previous literature.