Silicon-on-insulator technology has been used to fabricate 2 × 2 thermo-optic switches. The switch shows crosstalk of-23.4 dB and extinction ratio of 18.1 dB in the bar-state. The switching speed is less than 30 μs and the power consumption is about 420mW. The measured excess loss is 1.8 dB. These merits make the switch more attractive for applications in wavelength division multiplexing.