The invention provides methods for detecting and isolating phosphomolecules using phosphoaffinity materials that comprise a hydrated metal oxide. In an embodiment, a method for detecting a phosphomolecule in a sample involves (a) contacting a sample with a phosphoaffinity material comprising a hydrated metal oxide, under conditions wherein a phosphomolecule is capable of binding to the phosphoaffinity material to form a phosphomolecule-phosphoaffinity material complex, and (b) detecting formation of a phosphomolecule-phosphoaffinity material complex, thereby detecting a phosphomolecule in the sample. In another embodiment, a method for isolating a phosphomolecule from a sample involves (a) contacting a sample with a phosphoaffinity material comprising a hydrated metal oxide, under conditions wherein a phosphomolecule is capable of binding to the phosphoaffinity material to form a phosphomolecule-phosphoaffinity material complex, wherein the hydrated metal oxide comprises yttrium, and (b) separating the phosphomolecule-phosphoaffinity material complex from the sample, thereby isolating the phosphomolecule from the sample.