Disclosed is an apparatus for processing a surface of a substrate by subjecting the surface of a substrate to successive surface reactions of at least a first precursor and a second precursor. The apparatus includes at least one nozzle head having two or more two or more precursor zones for subjecting the surface of the substrate to at least the first and second precursors and a moving mechanism for moving the nozzle head in oscillating movement between a first end position and a second end position. The moving mechanism is arranged to store at least part of the kinetic energy of the nozzle head released in oscillating movement of the nozzle head.