TECHNOLOGY FOCUS - ELECTRICAL POWER AND ENERGY - Preferred Solution: When the solution is catalyst ink, the solution further comprises catalyst particle dispersed in the solvent, a proton-conducting material dissolved in the solvent (preferably alcohol or ketone) and binder. The weight ratio of carbon nanotubes in the ink to the catalyst particles is 1:100 - 500:1, 1:100 - 100:1, 1:10 - 10:1 or 1:3 - 3:1. The weight ratio of a proton-conducting material to the catalyst particle is 1:20 - 1:2. At least 1 (preferably at least 5, especially at least 75) wt.% of the particle is independent from the carbon nanotubes.Preferred Solid: (S1) Is a catalyst layer, which is porous. The solid material is proton-conducting material. (S1) Further comprises catalyst particles dispersed in the proton-conducting layer. The catalyst particles are located within 50 nm from at least one of the carbon nanotubes. The catalyst layer is a part of a fuel cell that includes a current collector, and the proton-conducting layer has a surface adjacent to the fuel cell current collector. The catalyst layer has a thickness of not more than 10 microns and is sandwiched between an electrolyte layer and a current collector.Preferred Assembly: (A1) Is a part of a solid polymer electrolyte fuel cell and further comprising an anode layer on one of the catalyst layers; and a cathode layer on the other of the catalyst layer.    TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Components: The catalyst particle comprises at least one of Pt, Pd, Ir, Ru, Os, Rh, Ni, Co, Mn, Mo, W, V, Ce or Ti. The catalyst particles have a diameter of 6-20 nm and are supported on one of carbon particles or conducting polymer particles. The catalyst particle is dispersed in the layer at greater than 12 (preferably greater than 20) or less than 10 mg/cm2.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Components: The carbon nanotubes have an inside diameter of 6 - 20 nm, where one of the catalyst particles or conducting polymer particles have a diameter larger than the inside diameter. The solvent is protic solvent and is selected from water, alcohol, aldehyde, ether, amine, ester or ketone. The carbon nanotubes in (S1) have a number of holes along their walls operable to communicate gas; have a length that is at least as large as the solid material layer thickness; and are operative to conduct electrical charge in the solid material. For (S1), at least a portion of the nanotubes is exposed to a surface of the solid material. The carbon nanotubes in (S1) have an inside diameter equal to or smaller than the catalyst particle diameter.Preferred Method: The dispersing step involves mixing carbon nanotubes (0.1 - 10 parts by weight per part of the metal catalyst particle).    TECHNOLOGY FOCUS - POLYMERS - Preferred Components: In the solution the solid dissolved in the solvent is polymer. The proton-conducting material in the ink comprises a perfluorosulfonic acid polymer or copolymer. The proton-conducting material in (S1) comprises perfluorosulfonic acid polymer or copolymer, sulfuric acid, sulfonated and phosphated polymers, metal oxides, metal phosphate, metal sulfates or metal hydrate.