The membranes create two compartments. The intermembrane space, as implied, is the region between the inner and outer membranes It has an important role in the primary function of mitochondria. which is oxidative phosphorylation.The membranes create two compartments. The intermembrane space, as implied, is the region between the inner and outer membranes. It has an important role in the primary function of mitochondria, which is oxidative phosphorylation