Nowadays, portable imaging surveillance systems are widely used in military and civil fields. Such systems always need low power consumption to meet the requirements of long-term operation. These systems are in standby mode during most of the time and woken up at a regular interval for a very short time to perform a measurement. Accordingly, a low power oscillator as wake-up clock generator is needed. In this paper, a sub-μW low temperature sensitivity RC oscillator is presented. Unlike the traditional CMOS RC oscillator with double comparators, it contains only one hysteresis comparator and operates in subthreshold region to reduce current consumption. The oscillator has been designed and simulated in a standard 0.18 μm CMOS process, achieving a frequency of 100 kHz. The variation of frequency is ±1:65% over the temperature range from -10°C to 110°C. The current consumption is 332 nA under a supply voltage of 1.8 V at room temperature. The occupied area is merely 0.01 mm<sup>2</sup> without pads.