Experimental results of hot-·wire measurements of turbulence in a supersonic shear layer are presented. A multiple-overheat single-wire method based on high-speed, computer-controlled sampling was used in order to obtain large sample sets in short time intervals. The Mach 3 main stream had a total pressure of 95 psia and a Re/cm of 2 x 10⁶. The Mach 1.7 secondary stream was injected parallel to the main flow at 10.7 psia, resulting in a slightly overexpanded flow. The injection slot had a height of 1.2 cm. The flow was monitored at four streamwise stations (x/H = .25, 4, 10, 20). The total temperature of the injected stream was varied from 300 K (equal to that of the main stream) to 420 K. The effects on the flow of these changes in density, velocity and temperature was investigated. Measured quantities included the mean and rms levels of the mass flux and total temperature. Nanosecond Shadowgraphs and spark Schlieren photographs were taken. The Favre-averaged velocity fluctuation, u^H, was also calculated. Small increases in absolute turbulence levels were seen in the heated flow, and the location of the maximum turbulence shifted significantly. Heating greatly enhanced the mixing in the shear layer and in the injected flow by the last station. An investigation of shock interaction with the shear layer generally resulted in elevated turbulence, but had little effect on. The measurement technique and reduction method proved accurate in the unheated flow, but greater uncertainty was found for the heated injection case.