Abstract: Items are coated with substantially homogeneous pyrolytic carbon by first heating them to the desired temperature, e.g., about 1200.degree. C. to 1600.degree. C. in a nonoxidizing atmosphere. A mixture of gas including an inert gas portion and a hydrocarbon portion is supplied to the heated enclosure at a rate so that the mixture approaches the temperature of the heated items and the hydrocarbon decomposes. The hydrocarbon portion includes between about 25 and about 60 volume percent acetylene and the remainder propylene. The exothermic characteristics of acetylene is such that the heat given off upon decomposition is sufficient to sustain the coating reaction.