Abstract: The present invention relates to an NCO-terminated polysiloxane prepolymer of the general formula (I) [(Q)q]-(M)m-(P)p—(R)r]t, in which R, P, M, Q, r, p, m, q and t are defined as follows: R in each case independently is at least one polyisocyanate unit and/or at least one diisocyanate unit, P in each case independently is at least one polyol unit, M in each case independently is at least one diisocyanate unit and/or at least one polyisocyanate unit, Q is at least one polysiloxane unit, r in each case independently is a number from 1 to 10, p in each case independently is a number from 1 to 10, m in each case independently is a number from 1 to 10, q in each case independently is a number from 1 to 10, t is an integer from 2 to 5, and the M units present are attached directly to the unit Q; to a process for producing said prepolymer, and to use as curing agent in a coating formulation.