The macroscopic yield stress of Ni3Al increases rapidly with temperature, reaching a maximum at about 700°C. Such anomalous behavior has been observed in other ordered alloys which undergo partial disordering with increasing temperature,e.g. Cu3Au. The long‐range order parameter,S, of stoichiometric Ni3Al powder was measured over the temperature range 25°C to 1000°C and great care was taken to ensure a fine particle size and thus avoid extinction effects. The results of this study showed that, in Ni3Al, S remains constant at about 0.93 over the entire temperature range investigated. This means that theories relating the strength of ordered alloys toSare not applicable to N