This work is devoted to a preliminary study on the feasibility of catalytic combustion for syngas fuelled gas turbines equipped with Mn-substituted hexaaluminate catalysts. Results of catalytic activity tests on combustion of CO-H-2 over BaMn1Al11O19 and La0.8Sr0.2Mn1Al11O19 are reported and analyzed by means of a mathematical model of the catalyst section of a hybrid combustor. Experimental activity levels are shown to be close to the operating requirements of the combustor.