Single crystals of YVO<sub>4</sub> with different doping concentrations of Yb (1.5, 3.0, 8.0, and 15.0 at. %) and with good crystalline quality (FWHM ∼43-55 arc sec of rocking curve) were grown by the optical floating zone technique. Refractive index measurements were carried out at four wavelengths as a function of temperature. The measurements show that as the doping concentration of Yb is increased, the refractive index varies marginally for n<sub>e</sub> whereas there is a significant change in the value of n<sub>o</sub>. The thermo-optic coefficient (dn/dT) was found to be positive with a value ∼10<sup>-5</sup>/°C, which is 1 order higher than that for the undoped YVO<sub>4</sub> crystal. The thermo-optic coefficient is higher for n<sub>e</sub> compared to that of n<sub>o</sub>. Also, a set of relations describing the wavelength dependence of the thermo-optic coefficient were established that are useful for calculating the thermo-optic coefficient at any temperature in the range 30°C-150°C and at any wavelength in the range 532-1551 nm.