This paper presents the results of studies of the kinetics of the conduction current in the pulsed regime of high-resistance KTP crystals with electrical resistivity (1–5)×1010 Ω cm, grown from solutions in a phosphate melt by a modified Czochralski method. It is established that, when the electric field is switched on, there is slow growth of the conduction-current pulse, whose leading edge is about 5.2 ms wide. In the electrooptic modulators of Nd:YAG lasers controlled by a driver with pulsed bias, the bias-pulse width usually lies in the range 50–300 μs. The conduction current through high-resistance KTP crystals does not exceed 100 nA in such a regime, and, as shown by our experiments on lifetime, there are virtually no limits on the use of modulators based on KTP crystals associated with their electrochromic degradation.