Herein we report on the experimental and theoretical study of pyrazole alkylation catalyzed by basic mesoporous materials. (Cs)Al-SBA-15 or DEAPTS/MCM-4,1 differing in textural properties and compositions, were found to be efficient catalysts for pyrazole alkylation with different reactive alkyl bromides under thermal activation. They constitute the first examples of modified molecular sieves catalyzing this highly used transformation, showing a higher catalytic activity than other previously reported catalysts. DEAPTS/MCM-41 whose catalytic centers are tertiary amines resulting in the best catalyst for the investigated reactions. Furthermore, the catalytic pyrazole alkylation has been clarified by studying the reaction mechanism using computational approach. (C) 2009 Elsevier B.V. All rights reserved.