The unlamped electrooptic coefficient r41of high-purity CdTe has been measured at 23.35 and 27.95 micros in the far infrared. The values obtained for n03r41are 9.4 × 10-11m/V at 23.35 µ and 8.1 × 10-11m/V at 27.95 µ. Using previously reported values for n0, the electrooptic coefficients are found to be 5.5 × 10-12m/V at 23.35 µ and 5.0 × 10-12m/V at 27.95 µ. These measurements extend the region of observed electrooptic effect from 16 µ, previously obtained using GaAs, to 28 µ using CdTe.