The preparation and characterisation of a cobalt (111) complex of octaaza ligand, 5, 5'-bis(4-amino-2-azabutyl)-1,9-diamino-3,7-diazanonane (octaam) is described. The base hydrolysis kinetics of bis cobalt(III) of octaam has been studied spectrophotometrically by the stopped-flow technique. A consequent reaction is observed in the base hydrolysis of the spiro-octaamine with the fast reaction having k(OH) = 3.55 M(-1)s(-1) and the slower reaction k(OH) = 0.72 M(-1)s(-1) at 298 K with DeltaH(#) = 89 kJ/mol for the fast stage and DeltaH(#) = 102 kJ/mol for the slow stage (I = 0.4 M NaClO4). The fast reaction is assigned to the hydrolysis of the trans diaqua and the slower to further hydrolysis of the remaining Cl ions. The reaction appears to proceed predominantly by a D-CB (dissociative conjugate base) mechanism.