The beam coupling and response time of reduced BaTiO3 are reported. The major carrier changes from hole to electron after reduction. The electro‐optic gain and effective trap density increase with the illumination intensity. Although the electro‐optic gain varies little, the response time τ decreases by a factor of 2.8 after reduction. Experimental results indicate that at least three energy levels including shallow level(s) exist in this BaTiO3.