Boronic esters are key intermediates in the synthesis of biologically active compounds such as thrombin and proteasome inhibitors. However, they have low hydrolytic stability both during synthetic reactions and in biological media. We report the preparation of several boronic esters and a comparative study of their stability to hydrolysis vs. the corresponding pinanediol boronic esters, which are among the most hydrolytically stable. We discovered that the boronic esters derived from (1,1'-bicyclohexyl)-1,1'-diol are the most stable among those examined.