This paper describes the design, construction, and testing of a concentrating solar collector based on the Stationary Reflector/Tracking Absorber (SRTA) principle. The system consists of a fixed, 2.5-m dia, spherical mirror which focuses solar radiation on a movable, cylindrical absorber tracking the sun. This work is an extension of earlier tests with a similar collector in which output temperatures up to 150°C were obtained with water. The present system, using a mineral-oil-based heat transfer fluid, was capable of heating the fluid up to 300°C under steady-state conditions. The direct radiation efficiency ranged from 50 percent at low temperatures up to 30 percent near 300°C, showing the SRTA to be an effective concentrating collector for the intermediate temperature range which can be constructed at relatively low cost.