An improved alkylation reaction chamber for contacting acid catalysts with alkylation reactants. A heat exchanger, a plurality of baffles and a plurality of spray nozzle assemblies are disposed within a vertically positioned, elongated vessel. Acid catalyst flows upward in serpentine fashion through the vessel and alkylation reactants are sprayed into the catalyst at a plurality of elevations within the vessel. Sprays are directed in substantially all directions so that maximum utilization of the available reaction chamber volume is effectuated. Exothermic heat of reaction is removed by the heat exchanger.