The invention provides a process for the preparation of an olefinic product, comprising: (a) reacting an oxygenate feedstock, in a reaction zone in the presence of a molecular sieve catalyst, at a temperature from 350 to 1000° C., to produce a reaction effluent stream, comprising at least oxygenate, olefin, water and acidic by-products; (b) cooling the reaction effluent stream by means of an indirect heat exchange to a temperature greater than the dew point temperature of reaction effluent stream; (c) further rapidly cooling the reaction effluent stream to a temperature lower than the dew point temperature of the reaction effluent stream by direct injection of an aqueous liquid into the reaction effluent stream, to form a first quench effluent stream; and (d) separating the first quench effluent stream into a first liquid quench effluent stream and a first gaseous quench effluent stream, comprising the olefinic product.