The supported nickel catalysts based on porous nickel ribbon with MgO underlayer were tested in tri-reforming of methane to synthesis gas (1 atm, 750 °C, CH4/CO2/H2O/O2/N2 = 24/18/18/3,5/36,5, GHSV = 62.5 L/gh). The predominant part of the supported nickel particles in the used catalysts remain in the state of dispersed crystallites epitaxially bound to MgO. Besides, highly dispersed nickel crystallites (2–3 nm) epitaxially bound to MgO also appear. These catalysts showed stable activity throughout the test period (9 h); after the reaction no carbon formation was observed. The resistance of these catalysts to carbon formation was attributed both to the formation of nickel crystallites epitaxially bound to MgO and to the formation of the MgO underlayer that covers the nickel ribbon and prevents its contact with the reaction medium.