Incorporation of diaryl diselenides (1a, b; R = H, Cl) into pentasil zeolite generated "extended" selenium-centered radical cations (1a(.+), b(.+)). These species are identified by their EPR (g(avg) = 2.0644, 2.0639) and diffuse reflectance spectra (lambda(max) = 520, 550, 950 nm). The relative strength of the two-center three-electron Se-Se bond is compared with the corresponding S-S bond in diphenyl disulfide radical cation.