Measurements are presented of (a) the emission density from clean and oxygen covered molybdenum surfaces as a function of the arrival rate of Ba or of Ba+BaO and of (b) the migration length of Ba and of Ba+BaO over oxygen covered molybdenum surfaces. The emission density is comparable to that obtained from similarly activated tungsten surfaces, but the minimum arrival rate of total barium required for complete surface coverage is much higher than for the tungsten case. The migration length is also comparable for the two systems.