Unmanned Aerial Vehicles (UAVs) have found many applications, both civilian and military. They can be used by armed forces, police, border guard, customs office, search and rescue units but also in scientific research, power and civil engineering and environmental monitoring. However, regardless of actual application, there is always a requirement for an observation system capable of providing visual data in low light, harsh weather conditions and during nighttime. In the paper the construction of high resolution thermal camera is presented, fitted with microbolometer 640x480 focal plane array operating in 8÷12
m spectral range. This lightweight and energy efficient device can be mounted onboard an UAV for observation, target detection and recognition in difficult weather and low light conditions and in low visibility situations caused by dust, smoke or fog. The described camera provides full day/night observation capability.