Complexes of general formulation [Cr(Schiff-base)(H₂O)₂]X, where Schiff-base=1, 2-bis(salicylideneamino)ethane (salen), 1, 3-bis(salicylideneamino) propane (salprn) and 1, 4-bis(salicylideneamino)butane (salbuen) and X=ClO₄ or Cl have been prepared and characterised. Single-crystal structure of the complexrans[Cr(salprn)(H₂O)₂]Cl has been resolved. Evidence for less distorted coordination geometry around chromium in the salprn analogue as compared to that intrans-[Cr(salen)(H₂O)₂]⁺ has been presented. The kinetics of the aqua ligand substitution in the complexes Cr(Schiff-base)(H₂O)₂⁺ by thiocyanate have been investigated under pseudo-first order conditions with [NCS⁻]≫[Cr(III)],T=10–50°C, [H⁺]=10⁻⁸−10⁻¹ M,I=1.0M (LiClO₄). An attempt has been made to discuss the anomalous lability oftrans-[Cr(salen)(H₂O)₂]⁺ reported earlier in comparison to the reactivities of salprn and salbuen analogues. Bimolecular rate constants for the aqua ligand substitution by NCS⁻ in [Cr(Schiff-base)(H₂O)₂]⁺ at 25°C vary by more than two orders of magnitude depending on the nature of the Schiff-base ligand. The reactivity order is discussed in terms of the possible steric strain imposed by the equatorially coordinated quadridentate ligand.