The optimization of the conventional synthesis of an important industrial product-methyl iodide-by using iron sponge, iodine, and methanol as precursors is presented. The experiments were carried out under different conditions of molar ratio of the reagents, reaction and distillation temperatures, stirring rate, and rate of addition of methanol. It is shown that the highest yield of the product is reached at the molar ratios of methanol/iron of 1.0 and iodine/iron higher of 1.5. The optimal temperature range for this synthesis is located between 53 and 109 degreesC for which the highest yields were obtained in coincidence with the temperature range at which the formation of FeI2 is also optimal. A relationship between the syntheses of FeI2 and the syntheses of CH3I was elaborated and it was found that the conditions favorable for the syntheses of FeI2 are also necessarily favorable for the syntheses of CH3I.