The composites of La_2/3Ca_1/3MnO₃:xSiO₂ (0⩽x⩽0.40) have been synthesized by sol–gel technique to derive homogeneous nanocomposites. Si⁴⁺ by virtue of its strong preference for tetrahedral site does not enter the perovskite lattice. The percolation threshold composition has been determined by resistivity measurements at around 90% volume fraction of LCMO. A detailed electrical, magnetic and magneto-transport characterizations have been carried out for composites around the threshold composition (x=0.05,0.10,0.15). The magnetoresistance results at 1T show a sharp peak at T_c and a minimum just below T_c as reported in several polycrystalline LCMO composites.