A facile one-pot synthesis route for preparation of a well-ordered cubic mesoporous silica SBA-1 functionalized with -COOH functional groups is reported for the first time. The results of Si-29{H-1} HETCOR NMR provide direct evidence for the interactions between the carboxylic acid and silanol groups in carboxylic acid functionalized SBA-1. Density functional theory calculations indicate that the T-3-Q(4)-Q(3) motif is the favorable framework composition in the material and the Carboxylic protons in the T-3 species can form hydrogen bonds with the spatially proximate oxygen atom in the Q(3) Si-OH species.