The fall in the Consumer Prices Index (CPI) measure of inflation to 1.5% marks the lowest in four-and-a-half years.
Falls in the cost of transport services, particularly air fares, were the largest contributor to the fall, the Office for National Statistics has said.
Heavy discounting by supermarkets also provided a large downward effect.
CPI equalled the rate seen in October 2009. It was last lower, at 1.1%, in September 2009.