The rate of formation of gaseous sodium sulphate from sodium chloride and the combustion of a sulphur-bearing fuel has been investigated in a controlled mixing history combustor. The reaction was studied in the residence time range 0–16 millisec to simulate conditions resembling those in a gas turbine combustion chamber. The results show that under the conditions investigated, gas temperature was the most significant variable affecting the reaction rate. Gas phase formation of sodium sulphate proceeds too slowly to contribute to sulphatic corrosion in the short residence times which occur in gas turbine combustion chambers. The results obtained, in conjunction with predictions of salt particle behavior in the gas turbine engine indicate that the deposition process on turbine blades occurs via passage of transient high concentrations of particles through the engine.