Next generation X-ray mission concepts (e.g. Lynx) call for a wide field X-ray imager with high detection efficiency from 0.2 keV to 10 keV and fast readout capability (< 10 Hz frame rate). In order to properly sample the planned fine angular resolution of the optical assembly (0:5″ HPD), small pixel sizes of less than or equal to 16 microns are required. Hybrid CMOS detectors are a type of active pixel sensor that is well suited to the high throughput and wide bandpass requirements of such instruments, and the pixel size goals are well within reach. In collaboration with Teledyne Imaging Sensors, the Penn State X-ray detector lab has developed new small pixel Hybrid CMOS sensors to meet these needs. These prototype 128 x 128 pixel devices have 12.5 micron pixel pitch, 200 micron fully depleted depth, and include crosstalk-eliminating CTIA amplifiers and in-pixel correlated double sampling capability. We report on characteristics of one of these new detectors, including read noise, energy resolution, and pixel-to-pixel gain variation. The read noise was measured to be as low as 5.54 e-± 0.05 e-, while the gain variation was found to be 1.12% ± 0.06%. The energy resolution, including calibration for gain variation, was measured to be as good as 148 eV (2.5%) at 5.9 keV.