(1-x)Ba0.5Sr0.5TiO3(BST)-xMg(2)TiO(4)(MT) composite ceramics have been prepared in situ by using a citrate-nitrate combustion process. X-ray diffraction data showed that neutral precursor with pH 7 is suitable for in situ formation of biphase structure with BST and MT. Curie temperature of the composite ceramics sintered at 1300 degrees C was close to or even higher than that of pure BST. Modeling with the modified effective medium approximation indicated that permittivity of BST in the composite was strongly dependent on the MT volume fraction (f(MT)), which can be described by the relation epsilon(BST) = a x e(bxfMT). The samples with compositions of 0.5 <= f(MT)<= 0.7 exhibited percolation transition. (C) 2015 Elsevier Ltd. All rights reserved.