The synthesis and characterisation of the new N,O-phenol-pyrazolepro-ligand, ^pzLH, comprising a pyrazole covalently linked to an o,p-di-tert-butyl-substituted phenol, are herein reported. In CH₂Cl₂ at room temperature, the cyclic voltammogram (CV) of ^pzLH exhibits a quasi-reversible one-electron oxidation process (at E_1/2 = 0.66 V vs.Fc⁺/Fc) attributed to the formation of the phenoxyl radical cation [^pzLH]˙⁺. ^pzLH reacts with M^II(BF₄)₂ (M = Cu, Co) in a 2 : 1 ratio to afford the bis-Cu^pzL₂ (1) and tris-Co^pzL₃ (2) complexes respectively. The X-ray structure of 1 reveals a Cu(II) ion in a square-planar trans-Cu^II-N₂O₂ coordination environment whereas that of 2 consists of a Co(III) ion with an octahedral mer-N₃O₃ coordination sphere; formed by the chelation of two (in 1) or three (in 2) N,O-bidentate phenolate ligands respectively. Both structures are preserved in CH₂Cl₂ solution, as revealed by their NMR (for 2) and EPR (for 1) data. The CVs of 1 and 2 consist of two (at E_1/2: 0.43 and 0.58 V vs. Fc⁺/Fc) and three (E_1/2 = 0.12, 0.54 and 0.89 V vs. Fc⁺/Fc) reversible one-electron oxidation processes, respectively. The one-electron electrochemical oxidation of 1 and 2 produces the oxidised species, 1⁺ and 2⁺, which are stable for several hours at room temperature under inert atmosphere in CH₂Cl₂. The UV/vis and EPR data obtained for 1⁺ and 2⁺ are unambiguously consistent with the latter being formulated as Cu(II)- and Co(III)-phenoxyl radical complexes, as [Cu^II(^pzL˙)(^pzL)]⁺ and [Co^III(^pzL˙)(^pzL)₂]⁺ respectively.