Here, we present platinum and palladium mononuclear complexes with EUV photosensitivity and lithographic performance. Many platinum and palladium complexes show little or no EUV sensitivity; however, we have found that metal carbonates and metal oxalates ( and ; or Pd) are sensitive to EUV. The metal carbonates give negative-tone behavior. The most interesting result is that the metal oxalates give the first positive-tone EUV resists based on mononuclear organometallic compounds. In particular, (dppm)Pd() (,1-bis(diphenylphosphino)methane) (23) prints 30-nm dense lines with of . Derivatives of (23) were synthesized to explore the relationship between the core metal and the resist sensitivity. The study showed that palladium-based resists are more sensitive than platinum-based resists. The photoreaction has been investigated for two of our most promising resists, (23) and (27). Our experiments suggest the loss of and the formation of a zerovalent complex upon exposure to light. We have identified as the main photoproduct for (23) and () as the main photoproduct for (27).