In this brief report we describe the observations of the eruption of the Tolbachik volcano by the NOAA 4 satellite. The NOAA 4 satellite carries among its sensors a very high resolution radiometer sensitive to radiation in the visible band (0.6 to 0.7 μ) and the thermal infrared band (10.5 to 12.5 μ) and has a resolution of 1 km at nadir. The signals are received at Gilmore Tracking Station near Fairbanks, Alaska. The Kamchatka peninsula is visible in at least one of the satellite orbits at about 2200 UT. The Tolbachik volcano, situated in the Kamchatka peninsula at 56°N and 160°E, erupted on July 6, 1975.