Copoly(2-oxazoline)-based photoresists are prepared from pEtOx80Bu=Ox20 and pPhOx80Dc=Ox20, respectively, a tetrathiol, and a photosensitive initiator. It is possible to prepare copoly(2-oxazoline)s bearing unsaturated side chains in a microwave reactor on a decagram scale in reaction times of 100 min or shorter. UV irradiation of dried polymer films through a quartz mask induces the thiol-ene reaction in the illuminated areas. Subsequent development of the polymer films in halogen-free solvents reproduces the negative pattern of the mask with a resolution of 2 μm. The pEtOx80Bu=Ox20-derived photoresists can also be developed in water.