1-Alkyl-2-(naphthyl-β-azo)imidazoles [β-NaiR; R = Me (a), Et (b), CH2Ph (c)] react with Pd(MeCN)2Cl2 to yield Pd(β-NaiR)Cl2(2), the i.r. spectra of which support the presence of a cis-PdCl2 configuration. The complexes react with catechols in the presence of Et3N to yield ternary complexes [Pd(β-NaiR)(O,O)] [O,O = pyrocatecholato (cat) (3), 4-t-butylcatecholato (tbcat) (4), 3,5-di-t-butylcatecholato (dtbcat) (5), and tetrachlorocatecholato (tccat) (6)], which were characterized by elemental analysis, i.r. and 1H-n.m.r. spectral data. Redox studies by cyclic voltammetry suggest the existence of four successive redox couples wherein two responses, positive to s.c.e. are due to catechol to semiquinone and semiquinone to quinone oxidation, respectively; the couples at negative to s.c.e. are referred to azo reductions. The complexes exhibit ligand-ligand charge-transfer transitions in the near-i.r. region. The band position is largely dependent upon the substitutent on the catechol frame and exhibits negative solvatochromic effects. The transition is qualitatively assigned as the HOMO (cat) → LUMO (β-NaiR) transition. This fact is also supported by theoretical calculations using the PM3 method.