The complex dielectric permittivity of aqueous NaOH (c less than or equal to 2 M) and of dilute (less than or equal to 0.6 M) NaAl(OH)(4) and NaB(OH)(4) solutions in NaOH ([Na] = 1 M) at 25 degrees C has been determined in the frequency range 0.2 less than or equal to v/GHz less than or equal to 20. All spectra could be represented by a single Cole-Cole relaxation time distribution attributed to the cooperative relaxation of the solvent. The concentration dependence of the effective hydration number of OH- has been determined. For aluminate and berate solutions the deduced parameters: effective conductivity kappa(e), static permittivity epsilon, relaxation time tau, and distribution parameter or suggest a 1:1 replacement of hydroxide by aluminate and berate, accompanied by a release of bound water. The lack of an ion-pair relaxation process despite notable ion association suggests that rapid proton exchange is important not only for the dynamics of OH- but also for Al(OH)(4)(-) and B(OH)(4)(-).