Silica catalysts modified with alkali metal oxide and alkaline earth metal oxide exhibited an excellent catalytic performance in the vapor phase intramolecular dehydration of N-(2-hydroxyethyl)-2-pyrrolidone to N-vinyl-2-pyrrolidone in the temperature range of 360-400 degrees C. The high activity and selectivity are considered to be due to the presence of both weak acid sites and weak basic sites on the modified SiO2. (c) 2005 Elsevier B.V. All rights reserved.