Factory gate prices dropped by 0.9 per cent last month, according to the Central Statistics Office.
The index, an indication of pipeline inflation, saw a decline of 0.7 per cent for the year. Export sales were also slower last month, declining 0.9 per cent while the index for home sales was down 0.7 per cent.
Office machinery and the computers sector saw the biggest monthly price decrease, down 3.8 per cent.
The biggest monthly falls were in the prices of energy products, and petrol fuels also fell compared with June.
On an annual basis, building materials prices grew by 10 per cent, with structural steel prices up 46.4 per cent and reinforcing metal prices 44 per cent higher.
The cost of fuels grew by 7.1 per cent in the 12 months to July, with petroleum fuel prices rising 10.7 per cent.
These annual rises were offset by a monthly easing in fuel costs in July 2004. Overall energy products were 0.3 per cent cheaper, and the cost of petroleum fuels dropped by 1.1 per cent.