Atomic hydrogen etching on the pulsed laser deposited (PLD) diamond-like carbon (DLC) films were examined in situ by using Raman spectroscopy. Thermal annealing of the as-prepared DLC films was found to alter the D-band (similar to 1355 cm(-1)) and G-band (similar to 1582 cm(-1)) from unresolved features at room temperature to clearly separated bands at above 500 degreesC, indicating graphitization of the films. The presence of atomic hydrogen retards graphitization at temperatures lower than 500 degreesC, presumably because reactive atomic hydrogen formed sp(3)-bonding carbons which prevented graphitization at below 500 degreesC, while at above 500 degreesC, the hydrogen etches away disordered structure of the DLC film as the intensity changes of the D-bands demonstrate.