A process for producing high purity acetic acid from a carbonylation reaction, wherein the carbonylation reaction is carried out while maintaining a low ethyl iodide content in the reaction medium. The ethyl iodide concentration may be maintained by removing acetaldehyde from the reaction medium and/or by adjusting at least one A) hydrogen partial pressure in the reactor, B) methyl acetate concentration of the reaction medium; and/or C) methyl iodide concentration of the reaction medium.