The reaction of thallium(I) salts (acetate, formate) with aromatic 1,2-diols R(OH)(2) (R = C6H4, C6Cl4, C6Br4, C6H2BU21, biphenyl-2,2’-diyl) yields Tl-2[O(2)R], Tl[OR(OH)], or Tl[O(2)R.] depending on the solution conditions and the nature of R. The compound Tl[OC12H8(OH)], derived from 2,2’-dihydroxybiphenyl, crystallizes in the space group C2/m, with a = 7.911(2) Angstrom, b = 10.775(3) Angstrom, c = 11.955(4) Angstrom, beta = 93.33(2)degrees, V = 1012.8(4) Angstrom(3), and Z = 2. Refinement converged at R = 0.0388, R(w) = 0.0445 for 639 reflections at 24 degrees C. The molecule is a dimer, based on a Tl2O2 ring. Only one OH of the diol is deprotonated, so that there is no chelation, and the lattice involves intermolecular Tl...HO bonding.