The pronounced catalytic effect of small particles of iron and other elements and compounds on the reaction of carbonaceous solids with various gases (02, CO-CO2, H20-H2) has been documented by a number of investigators reporting on thermogravimetric studies on bulk samples (1,2) and on optical and electron microscope observations of pitting or surface channeling by rapid local attack adjacent to sub-micron iron particles (3,4). In this work, emphasis has been placed on detailed electron microscope studies of Fe particle channeling on graphite exposed to “wet” and “dry” hydrogen at temperatures from 650°C to 1200°C.Flakes of freshly cleaved Ticonderoga graphite are coated with 40 - 1000 Å of Fe by vacuum deposition which forms spherical particles during subsequent annealing at 750°C.