The electronic structures of quasi-one-dimensional halogen-bridged mixed-metal compounds [Ni(1-x)Pd(x)(chxn)(2)Br]Br(2) were investigated by means of powder X-ray diffraction measurements. Unit cell lengths of all directions obeyed a linear relationship when x < 0.9, whereas those deviated when x > 0.9 especially in the case of the b and c axes. This deviation can be explained by a phase change from an M(III) Mott-Hubbard state to an M(II)-M(IV) charge-density-wave state because of chemical pressure caused by the substitution of Pd ions into [Pd(chxn)(2)Br]Br(2) with smaller Ni ions.