The acid-base properties of 10 wt% V2O5-SiO2 and 10 wt% TiO2-SiO2 binary mixed oxide aero- and xerogels were determined by studying the transformation of methyloxirane and 1-butane. The transformations (the isomerization of methyloxirane to propanal and the double-bond migration of 1-butene to form isomeric 2-butenes) indicate that all samples contain mainly acidic sites. Correlations are shown to exist between heteroconnectivity (derived from FTIR analysis) in conjunction with the textural properties and the catalytic performance.