Oil-in-water nanoemulsions were developed and evaluated for effectiveness in breaking down crude oil emulsions. The nanoemulsions were prepared using two types of ethoxylated nonionic surfactants: nonylphenol and lauryl ether, at a concentration of 12wt%, and the solvent xylene as the oil phase, at different concentrations (5, 7, and 10wt%). The results of the demulsification tests showed that the nanoemulsions developed are a viable alternative to break down petroleum emulsions, with efficiency ranging from 90 to 95%. Also, the greater the xylene concentration in the nanoemulsion, the faster the demulsification process was.