Viscosities of three tri-divalent complex salts, viz., hexamine-cobaltic sulphate, tris-eihylene­diamine-cobaltic sulphate and tris-propylenediamine-cobaltic sulphate, have been measured. The Jones and Dole equation is found applicable in dilute solutions. The value of 'A' found and that derived with Falkenhagen and Vernon's equation (in parenthesis) are : 0.045 (0.0413), 0.0518 (0.0487), 0.0542 (0.0512). The ionic conductance of tris-propylenediamine ion at 35o is 83.10 ohm-1. In extension of the previous work (this Journal, 1954, 31, 333) three complex tri-divalent salts that did not hydrolyse immediately were chosen for investigation.