libraries generated against the tert-butyl phosphonatehapten 2 and the chloromethyl phosphonatehapten 3 with pivaloyloxymethyl-umbelliferone 1 as a fluorogenic substrate led to the isolation of eleven catalyticantibodies with rate accelerations around kcat/ kuncat = 10(3). The antibodies are not inhibited by the product and accept different acyloxymethyl derivatives of acidic phenols as substrates. The