EPR and magnetic susceptibility measurements have been performed on xMnO center dot(100-x) [70TeO(2)center dot 25B(2)O(3)center dot 5SrO] glasses with 0.1 < x < 50 mol%. The number of isolated Mn2+ ions, participating at the g(eff)approximate to 4.3 resonance increases up to 1 mol% MnO and after that decreases to nil for 10 mol% MnO. The number of Mn2+ ions participating at the g(eff)approximate to 2.0 resonance increases when the MnO content rises. From line-width composition dependence of these glasses, for x >= 1 mol%, the manganese ions participate to the superexchange-magnetic interaction. Data obtained from magnetic susceptibility measurements confirm the obtained results from EPR for participation of manganese ions at the superexchange-magnetic interaction. Also, these data evidenced that in studied glasses with x > 1 mol% the manganese ions are in (2+) and (3+) valence states. The molar fractions of these ions increase with MnO content in the glasses. (c) 2006 Elsevier B.V. All rights reserved.