The amount of dollars purchased in the month by the central bank was the highest at USD 9.348 billion in the reporting month, RBI monthly data showed.
The apex bank sold USD 3.895 billion dollars in the spot market in July.
Last year in the same month, RBI was a net seller of the greenback after it purchased USD 50 million and sold USD 6.026 billion.
In June, RBI had bought USD 3.332 billion from the market while it sold USD 2.735 billion.
The central bank's intervention in the foreign exchange market is to curb volatility in the currency market.
In the forwards dollar market, the outstanding net forward purchase at the end of July stood at USD 5.397 billion as against sales of USD 154 million in the previous month.