An apparatus for producing a selective solar-absorbing coating on tubes is described. The coating has absorptance α = 0.88±0.02 and room-temperature emittance ε = 0.035±0.005. When applied to a glass substrate, it consists of layers of stainless steel, copper, and a composite metal–carbon layer. The coating is applied by translation of the substrate through two hollow-cathode magnetron sputter-coating chambers. The metal–carbon layer is applied by reactive sputtering in the presence of acetylene and has a graded refractive index. Coatings have been incorporated into evacuated tubular collectors and their properties are discussed.