This study concerns the analysis of environmental effects on the behaviour under monotonic and cycling loading of alloys based on FeAl and TiAl intermetallic compounds. Special attention is paid to the coupling of environmental and mechanical effects. In both types of loading, the species which is found to operate at ambiant temperature is water vapour. This species plays also a determining role in fatigue crack propagation at elevated temperature. Effects due to oxygen adsorption are also discussed.