NOVELTY - A method for producing particles having nano-sized grains, involves mixing a solution containing one or more metal cations with one or more surfactants to form a surfactant/liquid mixture and heating the mixture to form the particles.    USE - For production of particles having nano-sized grains such as cerium dioxide, complex metal oxides such as cerium magnesium oxide, cerium-samarium-copper oxide and lanthanum-calcium-neodymium-manganese-nickel oxide, used in solid oxide fuel cells (in cathode anode, electrolyte and interconnect), catalytic material (automobile exhausts, emission control, chemical synthesis, oil refinery, waste management), magnetic material, superconducting ceramics, optoelectric materials, sensors (e.g. gas sensors, fuel control for engines) and structural ceramics (e.g. artificial joints).    ADVANTAGE - The metal oxides produced have extremely small grain sizes, e.g. cerium dioxide materials, have grain sizes ranging between about 2 and about 10 nanometers. The metal oxides are highly crystalline, i.e. they have a high degree of atomic order, and extremely high surface areas compared to conventional metal oxides. Very complex, multi-component metal oxides can be produced, hence different atomic species are evenly distributed throughout the material. The process is performed at low temperatures (less than about 300 degrees C), thereby reducing capital costs for furnaces, operating expenses and avoiding undesirable sintering and grain growth that would occur at the high temperatures. The process is extremely rapid. The inorganic reaction and entire heat treatment may be done in as little as 30 minutes, as compared with conventional techniques that require long heat treatments. Long inorganic reactions are not used and therefore the process is much quicker than surfactant-templating processes. The process uses low cost raw materials and simple processing technology. The pore size distributions are very broad, and pore structure is therefore significantly different to that in the surfactant-templated materials.    DESCRIPTION OF DRAWING(S) - The figure shows heating profile during production of cerium dioxide particles having nano-sized grains.