The ketalization of polyols (glycerol, xylitol, xylose) in the presence of a number of heterogeneous acid catalysts has been studied. It has been shown that zeolite catalysts exhibit high activity in the formation of the acetone ketal of glucose in a flow system with the quantitative selectivity for the 1,2-product. The best catalyst is zeolite beta; in the presence of this zeolite and excess acetone, the yield is over 90% or, in the case of the structured reactor, even greater than 98% It has been shown that zeolite-based systems catalyze the formation of ketals of xylitol and xylose with a yield of up to 50% in the presence of excess acetone.