The synthesis of block copolymer monolayers at the surface of silicon oxide is described. Physisorbed monolayers of poly(epsilon-caprolactone) macroinitiators containing azo groups are used to start the radical chain polymerization of n-alkyl methacrylates in situ leading to the formation of amphiphilic surface-attached block copolymers. The characterization of the attached layers by surface plasmon spectroscopy, ellipsometry, infrared techniques, X-ray reflectometry, and water contact angle measurements is described. The macroinitiator technique can be used to prepare hydrophobic layers on hydrophilic substrates and allows one to circumvent some major limitations of the block copolymer physisorption process, such as solubility problems of the block copolymer and intrinsic Limitations of the layer thickness.