We have studied the field emission characteristics of chemically vapor deposited diamond thin films deposited on silicon substrate with tin-oxide (SnO2) as an overlayer. The diamond thin films were synthesized using the hot filament chemical vapor deposition method. The SnO2 coating on silicon substrate was prepared using Spray Pyrolysis technique. The diamond thin films were characterized by Raman spectroscopy and atomic force microscopy. The field emission current-voltage (I-V) measurements were performed in 'diode' configuration at a base pressure similar to1 x 10(-8) mbar. The diamond films with SnO2 overlayer exhibit better emission characteristics as compared with normal diamond films. Also, the turn-on voltage required to draw 0.1 muA current for such films was found to be similar to40% less than that deposited on normal silicon substrate. The surface roughness revealed by atomic force microscopy is found to be similar to4.5 and 4.0 nm for diamond films with and without SnO2 overlayer, respectively. (C) 2004 Elsevier B.V. All rights reserved.