Combination of steel and carbon enables to obtain a hybrid composite cable with increased strain in comparison with the carbon composite cables and decreased dead weight in comparison with the steel cables. Hybrid composite cable contains three layers: carbon fiber core, glass fiber reinforced plastic and steel wire strands. Carbon fiber core and steel wire strands take up tension stresses, acting in the cable during the exploitation. The functions of glass fiber reinforced plastic are distribution of transversal pressure of steel wire strands at the carbon fiber core, and taking up of tension stresses. Volume fractions of steel and carbon are determined basing on the assumption, that in an emergency, when the strain of carbon fiber exceeds the ultimate value and these fibers are disrupted, strands of steel wire must be able to take up tension stresses, acting in the cable. Hybrid composite cable could be rationally used in the structures, where all load bearing elements are axially tensioned, such as cable roofs. Hybrid composite cable based on steel and carbon was considered as a material for separate cable groups of saddle shape cable roof. Opportunity to decrease cable net materials expenditure was stated.