This paper presents a study of high temperature brittle intergranular fracture (HTBIGF) in which acoustic emission (AE) data and fractography were used together to make deductions about the dynamics of fracture. The AE event rate was proportional to the rate of overall crack growth, and the average crack increment per AE event correlated well with spacing of striations observed on the fracture surface. The AE from HTBIGF was also compared with ambient temperature brittle intergranular fracture and high temperature ductile fracture. The HTBIGF generated about 50% of the emission of fully brittle fracture, and at least an order of magnitude more than that from ductile fracture. The observation of discrete bursts of AE of this magnitude, coupled with the striations on the fracture surface, indicates that HTBIGF takes place in discrete brittle steps. This is consistent with the segregation of sulphur as an embrittling species to the region of the crack tip, promoting stepwise decohesion, rather than a continuous crack growth process.