We propose a method to compute an equilibrium solution for the monocentric city model with traffic congestion, and to quantify the im- pact of cordon tolls on social surplus. The focus of this paper is on the comparison of road pricing of one and two cordons, with the no toll and first-best situations as benchmarks. We find that a one-cordon toll yields a social efficiency of 63% with respect to first-best, and that an optimal two-cordon toll increases the efficiency to 73%. Both policies have a pos- itive impact on CO2 emissions because they reduce the average length of trips and reduce the road size.