The present work is the first ever study where the influence of beryllium (Be) addition on the stability of Mg alloy foam was investigated. Mg-3Ca alloy foams were produced by the liquid processing route with and without Be micro-addition. CaCO3 was used as a blowing agent. Mg-3Ca alloy foam without Be resulted in stable foam but exhibited low expansion with poor foam structure. Be addition significantly increased foam expansion and improved their structure. The expansion and the structure of the Mg foams obtained are comparable with that of commercially available aluminum foams. The XPS analysis confirmed the presence of BeO at the gas–solid interface of Mg foam. Be stabilizes the gas–solid interface of the foam by forming a smooth and crack-free surface of BeO layer which prevents the continuous oxidation of liquid foam and also minimizes the loss of blowing gas thereby enhancing the stability of Mg-3Ca alloy foams.