A novel approach towards thin-layer molecularly imprinted polymer (MIP) composite membranes was developed based on using benzoin Et ether (BEE), a very efficient a-scission photoinitiator. The triazine herbicide desmetryn was used as the template, and a mixt. of the functional monomer 2-acrylamido-2-methyl-1-propane sulfonic acid (AMPS) and the cross-linker N,N'-methylene-bis-acrylamide (MBAA) in methanol was copolymd. via photoinitiation followed by deposition on the surface of either hydrophobic or hydrophilically precoated polyvinylidene fluoride (PVDF) microfiltration membranes. Blanks were prepd. under identical conditions, but without the template. Esp., the degree of functionalization (DF) of the PVDF membranes with poly(AMPS-co-MBAA), the membrane permeabilities and non-specific vs. MIP-specific template binding from aq. solns. during fast filtration were studied in detail to evaluate the effects of the prepn. conditions, in particular the coating of the membrane surface with the photoinitiator prior to UV irradn. and the influence of the precoated hydrophilic layer on PVDF. Significant template specificities of the MIP membranes compared with the blanks were only achieved for the prepns. including coating the two types of PVDF membranes with BEE. In contrast, a homogeneous photoinitiation of the copolymn. in the membrane pore vol. yielded functional layers with similar DF but with only non-specific desmetryn binding. All data clearly indicate the significant contribution of MIP stabilization by the support material in layers of optimum thickness to the MIP specificity. Main advantages of the novel approach are the potential to synthesize MIP composite membranes by controlled deposition onto any kind of polymer support, and the very fast MIP prepns. due to a very efficient photoinitiator and small MIP layer thickness. Due to the mech. and chem. stability in combination with high permeabilities, thin-layer MIP composite membranes have a large application potential, e.g., in solid phase extn.