A few compositions of perovskite oxide BaSn(1-x)Nb(x)O(3) (with x <= 0.10) system, prepared by solid state ceramic method, have been studied employing XPS and Mossbauer spectroscopy techniques. Mossbauer spectra of these compositions in the temperature range of 78-300 K reveal that the oxidation state of Sn is +4. In XPS measurements, compositions with x <= 0.010 show no evidence of Nb(5+) signal whereas the compositions with x >= 0.050 show clear evidence of Nb(5+) signals indicating some unreacted Nb(2)O(5) component in the system. This confirms the earlier report where presence of small amount of unreacted Nb(2)O(5) was predicted. (C) 2007 Elsevier Ltd. All fights reserved.