Monte Carlo molecular simulations in the NpNAT ensemble are performed to calculate the interfacial tension of water/n-dodecane, water/toluene, and water/(50wt% n-dodecane+50wt% toluene) at 1.83 MPa and temperatures ranging from 383.15 K to 443.15 K. Interfacial tension simulations of water/n-decane and water/benzene are carried out to benchmark force fields. The combination of the TraPPE forceeld and TIP4P/2005 water model overestimates the interfacial tension of water/n-decane and water/benzene at high temperatures. Modications of Lennard-Jones cross-interaction parameters are made to yield good agreement between experimental and simulated interfacial tension of water/n-decane and water/benzene.