Polymerization of THF catalyzed by solid acid in the presence of acetic anhydride was studied. A moderate Lewis acid catalyst produces required PTME (PTMG-acetate) having adequate M-n. Zeolitic material is not suitable for this production because very high molecular weight PTME is co-produced. From this aspect, mixed oxide materials show good performance because only these have the required acidic character. Mass-transfer study suggests the importance of pore size of support and the homogeneity of active sites. They affect on the M-n and the M-w/M-n strikingly. The commercial technology has established by utilizing these results.