In this paper a green potentiometric method is proposed for the determination of the iodine number of biodiesel. The solvent used is simply a water–ethanol mixture (1:1 v/v) and the reagent is iodine. The analytical procedure can be performed even without a laboratory hood as no iodine vapors are released if the method is done as indicated. The analytical results obtained with this procedure were compared with those from Wijs’ method. In order to strictly compare instrumental procedures potentiometry was also applied to the Wijs’ procedure. Also for comparison purposes a green visual method was applied. Statistical comparison of the four methods, through the paired Student’s t test and the F test of Snedecor showed excellent agreement among all of them.