To satisfy NASA deep-space communications needs, a readout integrated circuit (ROIC) optimized for single-photon counting (SPC) freespace optical communications will be developed, which is optimized for acquisition, tracking, ranging, and reception of the 1064 nm 1570 nm optical radiation used for freespace optical links. The ROIC will allow simultaneous recovery of photon time of arrival and spatial localization data that can be used for lasercom optical links, data recovery, and range measurements, even in the presence of high photon flux rate objects in the field of view. In Phase I, after developing a rigorous requirements document and confirming a controlled specification, a low-cost ROIC will be developed to couple to single-photon-counting detector arrays. The ROIC pixel circuits will be designed and simulated, as will key circuits, such as serializers, downsamplers, decision circuits, up/down counters, time-to-digital converters (TDCs), etc. When appropriate, circuits from existing ROICs will be demonstrated and characterized to show performance and proof of concept. At Phase I end, a preliminary design review will be conducted.