We have characterized the wavelength dispersion of the high- and low-frequency values of the linear electro-optic coefficient rc = r33−(no/ne)3r13 of poled 0.88 Pb(Zn1/3Nb2/3)O3–0.12 PbTiO3 single crystal. The measurements have been investigated as a function of the laser wavelength from 0.465 to 1.32 μm. Clamped rS and unclamped rT values of the electro-optic coefficient as well as the acoustic contribution ra have been established. We obtained a ratio of rS/rT = 30%, which is independent of the wavelength of the light beam. The value of rSc at the wavelength of 633 nm was found to be equal to 50±5 pm/V, which is a rather high value.