Wetting characteristics of crude oil droplets over limestone substrates in the presence of different aqueous solutions are investigated in terms of wetting length, droplet depth, contact angle, and spreading coefficient. A wide range of concentration of NaOH, Alcoflood polymer, and nonionic Triton X-100 surfactant are used as a continuous phase for the crude oil droplet. NaOH and Triton X-100 significantly enhanced the spreading characteristics of the crude oil droplet; however, AF1235 polymer caused a huge reduction in the spreading behavior of crude oil. (C) 2003 Elsevier Science (USA). All rights reserved.