A reaction cell with short optical path and oxygen electrode compartment for convenient quantitative determination of oxygen binding by hemoglobin.

1. A simple and compact apparatus, with which the oxygen equilibrium of hemoglobin can be determined easily, was constructed and its performance was examined. 2. The oxygen partial pressure and the degree of oxygen saturation in a hemoglobin solution were determined by combined used of a Clark oxygen electrode and a spectrophotometer. 3. This apparatus can be used in a usual 1 cm square cell holder of a commercial spectrophotometer without any modifications, and has the advantage that the light path length of the optical cell is variable and can be shortened to about 2 mm.