The performance of a recently developed indium antimonide (InSb) two-dimensional multiplexed medium wavelength infrared (MWIR) hybrid focal plane array (FPA) is presented. The CMOS FET switch array multiplexer individually buffers each detector in a 64 x 64 element array through a source follower amplifier. This multiplexer was designed for demanding low-background, high sensitivity requirements. The detector array consists of InSb photodiodes spaced on 100 micron centers, bump bonded through indium columns to the silicon multiplexer, and is thinned for backside illumination. The array is responsive to radiation in the 1 to 5.5 micron region. The FPA has been demonstrated to have a near theoretical read-out noise performance of less than 500 electrons. The, charge storage capacity is approximately 4 million electrons giving a dynamic range of 78 dB. The device is linear to better than 99.95%over the lower 30% of its dynamic range, and greater than 90% over its total range, reflecting the capacitive discharge nature of the charge integration. Dark currents of less than 10 pA are obtained at 77K with reverse biases as great as 0.5V, and less than 0.2 fA at 25K. Quantum efficiency greater than seventy-five percent has been achieved at the peak wavelength. Functional element yields of 99% have been obtained.