Patterned hydrogel structures have potential application in microfluidics, tissue engineering, and other soft matter technologies. In this study, we describe a novel photopatterning of thick cross-linked poly( 2-hydroxyethyl methacrylate) hydrogels through spatial manipulation of polymerization kinetics. Specifically, patterned hydrogels were fabricated by creating an inverse photomask in which the mask allows the initiating light to pass through all areas, but at different intensities. High light intensities, corresponding to the "unwanted regions", cause significant deviations in the polymerization kinetics to result in longer polymerization times compared to lower light intensities. This difference in polymerization kinetics is sufficient to create patterned structures. The novelty of this technique is that monomer molecules are consumed across the solution even in the "unwanted regions", minimizing the adverse effects of diffusion in traditional photolithography. As a result, patterns in relatively thick ( similar to 760 mu m) gels can be achieved.