A cylindrical ultrasonic array has been developed for operating environments that can reach extremes of 175 C and 20,000 psi. The array is a key component of the PharUSIT* (Phased Array Ultrasonic Transducer for Inspection of Tubing), a research demonstrator developed for borehole applications. The full array consists of 800 elements (10 rings of 80 elements each) and can provide a whole range of beam-forming versatilities and capabilities in 3-D, such as variable focusing, beam steering, electronic scanning, etc, all accomplished without mechanical movements. Special piezo-composites have been developed for the transduction layer, and new polymeric composites have been formulated for the backing material. The center frequency was chosen to be about 500 kHz to accommodate attenuation of the propagation media. A novel technique utilizing custom flexible circuit provides electrical connections between the array and the front-end electronics. Special fabrication processes have been developed to construct the array in a cylindrical geometry. A customized testing protocol has been implemented to demonstrate the survivability of the array technology and to evaluate the performance characteristics of individual elements under high-temperature/high-pressure conditions. The unique experimental setup will be presented. Data from electroacoustic measurements such as electrical impedance, bandwidth, sensitivity, angular directivity, and inter-element cross-talks will be shown. *EC GROW project PharUSIT (GIRD-CT-2002-000689)