We explore the possibilities of hydrogen evolution by basal planes of 2D metal dichalcogenides and oxides in the 2H and 1T class of structures using the hydrogen binding energy as a computational activity descriptor. For some groups of systems like the Ti, Zr, and Hf dichalcogenides the hydrogen bonding to the 2H structure is stronger than that to the 1T structure, while for the Cr, Mo, and W dichalcogenides the behavior is opposite. This is rationalized by investigating shifts in the chalcogenide p levels comparing the two structures. We find that usually for a given material only at most one of the two phases will be active for the hydrogen evolution reaction; however, in most cases the two phases are very close in formation energy, opening up the possibility for stabilizing the active phase. The study points to many new possible 2D HER materials beyond the few that are already known. H ydrogen holds a crucial place in many chemical syntheses and in energy production; 1,2 however, an economical process for hydrogen production has not been fully realized yet. One of the main challenges lies in finding a cheap catalyst that can evolve hydrogen efficiently. Platinum, which is known to be one of the best catalysts for hydrogen evolution, is prohibitively expensive, thus precluding it to be used on large scales. Several other metals, metal surface alloys and metal oxides, have been studied for the same reaction, but unfortunately most of these are not both efficient and cheap at the same time. 3−5 Only recently a few and interesting candidates have been identified for hydrogen evolution reaction (HER), for example, Ni 2 P. 6,7