A series of choline (Ch)-exchanged heteropoly acids (HOCH2 CH2 N(CH3 )3 )x H(6-x) P2 W18 O62 [abbreviated as Chx H(6-x) P2 W18 O62 , x=1-6] was synthesized and used as catalysts for the reaction of α-angelica lactone (alpha-AL) with n-butanol to form butyl levulinate (BL). The solubility of Chx H(6-x) P2 W18 O62 in the reaction mixture was temperature dependent: The catalysts were soluble under the reaction conditions and precipitated upon cooling of the reaction mixture. This facilitated recovery of the catalysts from the liquid phase. Importantly, an increase of the Ch content caused a decrease of the catalyst solubility. Catalytic activity of Chx H(6-x) P2 W18 O62 for the reaction with n-butanol appeared to be in good agreement with the concentration of Brønsted-acidic sites. The results suggest that the reaction proceeded through formation of pseudo-butyl levulinate as intermediate. Ch2 H4 P2 W18 O62 exhibited the best balance between catalytic activity and temperature-dependent solubility. The yield of BL reached 79.4 % at full conversion of alpha-AL at a moderate temperature of 75 °C in an open system. Chx H(6-x) P2 W18 O62 could be successfully reused five times without significant loss of activity.