Ethylbenzene is produced by the alkylation of benzene with ethylene in the presence of an alkylation catalyst having a particular structure defined by its X-ray diffraction pattern. A preferred catalyst is the zeolite MCM-22. The process is typically carried out at a temperature of 300.degree. to 1000.degree. F. but the catalyst provides sufficient activity for the reaction to be carried out at temperatures below 700.degree. F. Liquid phase operation is preferred, giving a lower yield of polyethylated products. The use of the selected catalyst also results in a reduction of the xylene impurity level to values below 500 ppm in the product.