A fiber-optic Bragg grating (FBG) sensor is proposed to measure the local static temperature (θ) over bar (s) and the fluctuating temperature theta(s) on the surface of a heated circular cylinder subjected to a cross-flow. In order to validate the new technique, a type-K thermocouple and a single hot wire are used to measure (θ) over bar (s) and the near-wake streamwise fluctuating velocity u, respectively. The FBG sensor measurement of (θ) over bar (s) agrees well with that simultaneously obtained by the thermocouple. The theta(s)-spectrum exhibits a prominent peak at the vortex shedding frequency, f(s)* = f(s)d/U-infinity approximate to 0.2 (U-infinity is the free-stream velocity and d is the cylinder diameter), consistent with the u-spectrum. In fact, the theta(s) and u signals are almost perfectly correlated at f(s)*. Furthermore, the measured (θ) over bar (s) and root mean square value of theta(s) are agreeable with previously reported Nusselt number data. These results demonstrate that the FBG sensor can be used to measure reliably both static and fluctuating temperatures. It is expected that the FBG sensor, because of its uniqueness in many aspects and being at an affordable cost, has an excellent prospect in temperature measurements. (C) 2003 Elsevier Science Ltd. All rights reserved.