A detailed survey of the applicable information concerned with the design of a photosynthetic gas exchanger capable of supplying the oxygen requirement for man confined in a space vehicle has been conducted. It is revealed that, from the biological point of view, there is sufficient knowledge of the photosynthetic mechanism as conducted in the microorganism, algae, to demonstrate the gas exchange equivalence of a man-algae system. The need exists today for applying this knowledge to an engineering design such that an efficient light-weight apparatus may be constructed. Major engineering problems exist in the selection of the light energy source, the chamber geometry, gas exchange and separation techniques, and the fundamental differences resulting from operation of a gas-liqui system in an environment of zero gravity. It is concluded from this evaluation that an engineering approach to these and other problems which will of a certainty arise as the development proceeds, will result in a successful algal system.