Alkali-metal exchanged M-ETS-10 (M= Li, Na, K, Rb, Cs, and Ba) molecular sieves have been investigated by different techniques such as X-ray diffraction, FTIR, TPD, and XPS. It is found that the overall Lewis basicity in M-ETS-10 increases as the cation is changed from Li to Cs in the alkali cation series. FTIR spectra and TPD of adsorbed CO2 indicate the presence of different types of adsorbed CO2 species. XPS studies reveal an increase in the extent of destabilization of O 2p valence levels from Li-ETS-10 to Cs-ETS-10 systems. A strong overlap is observed between Cs 5p and O 2p valence bands. Catalytic activity of Pt supported on M-ETS-10 for n-hexane conversion to benzene increases with the basicity of the support and the same is correlated with the FTIR, TPD, and XPS results.