The invention provides a process for the preparation of an olefinic product, the comprising: (a) reacting an oxygenate to produce an effluent stream, comprising at least oxygenate, olefin, water and acidic by-products; (b) cooling the effluent stream by means of an indirect heat exchange to a temperature greater than the dew point temperature of effluent stream; (c) further rapidly cooling the effluent stream to a temperature at or lower than the dew point temperature of the reaction effluent stream by direct injection of a first aqueous liquid into the effluent stream, to form a quench effluent stream; (d) separating the first quench effluent stream into a liquid quench stream and a gaseous quench stream; and passing the gaseous quench stream into a quench tower and contacting the gaseous quench stream with a second aqueous liquid, to produce a quench tower gaseous stream comprising the olefinic product.