Details are given of the construction of an evaporated nickel bolometer. These bolometers are approximately 200A thick and are evaporated onto a nitrocellulose pellicle approximately 1000A thick. The pellicle is supported on a glass base in which is a sandblasted groove. This groove is immediately below the area of the pellicle which is covered with the bolometer strip. The techniques are described which were used to measure the bolometer characteristics. The sensitivity and frequency response of the bolometer are discussed. A typical bolometer has a time constant of 0.004 second, and a threshold of 3.3×10−8watt for radiation modulated sinusoidally at 30 cycles per second where the band width of the system is 100 cycles.