Wetting transition of water on graphite and boron-nitride (BN) surfaces is investigated by molecular dynamics simulation. In particular, we report the effect of temperature and system size on the contact angle of water droplet on the two surfaces. Wetting temperature of water on graphite is found to be 470 +/- 5K, which is in good agreement with the estimate of Zhao (Phys. Rev. B 76 (2007) 041402) using grand-canonical Monte Carlo simulations. On the other hand, wetting temperature of water on BN surface is estimated to be lower, 438 +/- 5K. Temperature dependence of line tension of water droplet on both the surfaces is also studied, and found to vary between 10(-10) and 10(-9)N for temperature in the range of 300-420K. In this work, line tension for water on graphite and BN surfaces is observed to have a logarithmic proportional behavior with the contact angle. (C) 2010 Elsevier B.V. All rights reserved.