A large scale cylindrical asymmetric capacitively coupled plasma reactor is suitable for efficient treatment of materials like polymers, textile and plant seeds. Plasma is homogeneous and stable from transitions to streamers providing uniform and safe treatment of sensitive materials. For many biomedical and textile treatment effects, role of extremely reactive atomic oxygen species is very important. Measurements were preformed using nickel catalytic probe placed side-on to the powered electrode. Concentrations of neutral oxygen atoms were measured for a range of powers given by the RF generator, at several different distances from the powered electrode, in air at two different pressures.