NOVELTY - Catalyst structure comprises dispersed metal catalyst on support, where the support but not the metal catalyst can be observed using x-ray diffraction, and the metal catalyst can be chemically detected.    USE - The catalyst structure is useful in fuel cell catalyst.    ADVANTAGE - The catalyst structure is: inexpensive, well tuned and flexible; and yields catalysts of high metal dispersion.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are also included for:    (1) catalytically active material comprising a high surface area support, comprising: an oxide, carbide or nitride; and up to 20 wt.% of at least one catalytic metal;    (2) a process (P1) for making a catalyst structure, comprising: combining a compound that decomposes to yield gaseous reducing species, a catalytic metal precursor compound and a catalyst support precursor compound; and heating the combined compounds to form the catalyst structure comprising dispersed metal catalyst on the support in a same step;    (3) a process (P2) for making supported metal catalysts having less than 50 wt.% catalytic metal, comprising: (a) creating a physical mixture comprising a compound that decomposes to yield gaseous reducing species, a catalytic metal precursor compound and a compound that when thermally decomposed creates a thermally stable high surface area ceramic; (b) heating mixture in an inert gas atmosphere to a temperature greater than a thermal decomposition temperature of the compound that decomposes to yield gaseous reducing species; and (c) heating for a period of time for the supported metal catalyst to fully form from the compounds in the mixture; and    (4) an aerosol process (P3) for making supported metal catalysts having less than 50 wt.% of catalytic metal, comprising: the step (a) as above per se; creating a gas/solid aerosol of the above mixture and an inert gas; passing the aerosol through a high temperature zone having a temperature above the decomposition temperature of the compound that decomposes to yield the gaseous reducing species; and heating for a time in the high temperature zone for the catalyst to fully form from the mixture.