The present paper deals with an experimental study of the viscous-inviscid interaction occuring in a corner region under hypersonic, low density, free stream conditions. The tests were conducted in the Mach 11.8 hypersonic tunnel at PIBAL over a range of free stream Reynolds numbers between 0.15 x 10 to the 6th and 0.50 x 10 to the 6th/ft. The model consists of two sharp edged plates mounted at an angle of 90 degrees with respect to each other and with normal leading edges. Data obtained include surface measurements of pressure and heat transfer for values of the interaction parameter between 1.0 and 20. The entire corner region is surveyed at a value of 2.5 and measurements of total temperature, pitot, and static pressure are obtained. The results indicate that the static pressure in the region of intersection of the shock layers is as much as twice that of the local two dimensional value. The local heat rates in this region are also considerably larger than their two dimensional counterparts. (Author).