Sellmeier coefficients are necessary to optimize the design parameters of optical devices. These coefficients ar ecomputed for binary tellurite glasses to findthe chromatic dispersion behavior at any wavelength, particularly at the optical windows of optical fiber communication systems and femtosecond technology. A single-oscillator DiDomenico and Wemple’s dispersion equation is not sufficient to represent accurately the meausred refractive indexes throughout the transmission rnage. As a minimum, a two-pole Sellmeier equation is necessary to represent the data more accurately. Both the average electronic absorption band gap and the lattice absorption freqeuncy, lying in the UV and IR region, respectivley, affect the refractive indexes and their dispersion. Various other optical properites are discussed. A single-oscillator dispersion equation is unable to verify theexistence of zero-dispersion wavelength.