We introduce two methods for the visualization of phosphorylated proteins using alkoxide-bridged dinuclear metal (i.e., Zn²⁺ or Mn²⁺) complexes as novel phosphate-binding tag (Phos-tag) molecules. Both Zn²⁺– and Mn²⁺–Phos-tag molecules preferentially capture phosphomonoester dianions bound to Ser, Thr, and Tyr residues. One method is based on an enhanced chemiluminescence (ECL) system using biotin-pendant Zn²⁺–Phos-tag and horseradish peroxidase-conjugated streptavidin (HRP–SA). We demonstrate the electroblotting analyses of protein phosphorylation status by the phosphate-selective ECL signals. Another method is based on the mobility shift of phosphorylated proteins in SDS-PAGE with polyacrylamide-bound Mn²⁺–Phos-tag. Phosphorylated proteins in the gel are visualized as slower migration bands compared with corresponding dephosphorylated proteins. We demonstrate the kinase and phosphatase assays by the phosphate-affinity electrophoresis (Mn²⁺–Phos-tag SDS-PAGE).