We have made determinations of concentration profiles of HOCl in the Earth's stratosphere, including the diurnal variation. Measurements of the rotational Q2 branch at 99.5 cm-1 and of five RR(J3) transitions between 143 and 159 cm-1 were made using far infrared thermal emission spectroscopy. The spectra were obtained during a balloon flight of the FIRS 2 far infrared Fourier transform spectrometer and telescope from Palestine, Texas, on May 12--13, 1988. From these measurements, we obtain altitude profiles of HOCl from 23 to 42 km. We present daytime and nighttime average profiles of HOCl, as well as measurements on a 30-min time scale through the sunset transition at a single (35 km) altitude. Our measured profiles are lower than the current predictions from several modeling groups by a factor of approximately 0.6. ¿ American Geophysical Union 1989