Mesoporous SBA-15 materials have been synthesized with different pore sizes and characterized by X-ray diffraction, NZ adsorption isotherms, X-ray fluorescence and thermal gravimetric analysis. SBA-15 has been aluminated by grafting AlCl3 to SBA-15 in the presence of ethanol. Cupric ions have been introduced into these materials by aqueous ion-exchange. The electron spin resonance (ESR) spectrum of as-synthesized Cu-AlSBA-15 materials shows an axial g factor for Cu(II), and. the g and hyperfine parameters show that the cupric ions have octahedral or square pyramidal symmetry. ESR and electron spin-echo modulation spectra have been analyzed to determine the coordination geometry of adsorbates including CH3OD, D2O, ND3, (NH3)-N-15, and C2D4 to cupric ions.