The structure of the Zn2+ species in concentrated aqueous solutions of NaOH, KOH, RbOH, and CsOH was investigated with extended X-ray absorption fine structure (EXAFS) spectroscopy. The results show that the Zn2+ species exist in a tetrahedral configuration with a Zn-O bond distance of 1.96 +/- 0.01 Angstrom, independent of the cation of the hydroxide electrolyte. No evidence for higher Zn-H2O coordination shells, aggregation of the Zn(OH)(4)(2-) tetrahedra, or Zn-Zn interactions were found. The necessity of including the multiple-scattering contributions to obtain a complete and correct EXAFS analysis is clearly shown.