An organic acid composition for use in oil industry activities, said composition comprising: methane sulphonic acid; a metal iodide or iodate; and an alcohol or derivative thereof. The uses include: injection/disposal in wells; squeezes and soaks or bullheads; acid fracturing; acid washes or matrix stimulations; fracturing spearheads (breakdowns); pipeline scale treatments; cement breakdowns or perforation cleaning; pH control; and de-scaling applications.