Two organo-inorganic hybrid manganese(II) vanadates [Mn(phen)(2)(VO3)(2)](infinity) (1) and [{Mn(bipY)(VO3)(2)} [VO2(bipy))(VO3)(V2O6)](infinity) (2) were synthesized hydrothermally. Compound 1 is a chain consisting in VO3 units propagating along the b axis, decorated with {Mn(phen)2}(+2) subunits. Compound 2 is a ladder like structure propagating along the a axis, consisting of two helical chains connected by the heterobinuclear [Mn(bipy)VO4 (2,2'-bipy)] moieties, generating a double helical structure. Magnetization measurements reveal that dominant antiferromagnetic interactions are mediated between the manganese(II) centers for both structures through oxovanadate bridges. Magnetic data of compound 1 were fitted with the analytical expression for a regular chain model, estimating a J value of -0.30 cm(-1). The DAVE code was use to fit experimental data and calculate the values of the super exchange constants for 2, assuming four different exchange pathways, J(12) = -0.17 cm(-1): J(23) = -0.12 cm(-1); J(13) = -0.08 cm(-1); J(24) = 0.05 cm(-1). DFT calculations on a tetranuclear fragment of 2, using diamagnetic substitutions, gave super exchange values of J(12) = 17.5 cm(-1) and J(23) = 8.5 cm(-1), corroborating the antiferromagnetic nature of the interactions as observed experimentally. (c) 2012 Elsevier Ltd. All rights reserved.