The rupee depreciated by 30 paise to close at 81.77 (provisional) against the US dollar on Thursday, as participants remained cautious ahead of the release of the US inflation data.

Forex traders said a weak trend domestic equities also weighed on investor sentiments.

At the interbank foreign exchange market, the local unit opened at 81.61 and witnessed a high of 81.54 and a low of 81.92.

It finally settled at 81.77 against the American currency, registering a fall of 30 paise over its last close of 81.47.

"Rupee came under pressure in the first half of the session ahead of the US inflation number that will be released today. Expectation is that inflation could come in lower and that could keep gains capped for the dollar," said Gaurang Somaiya, Forex & Bullion Analyst, Motilal Oswal Financial Services.

Also, market participants remained cautious ahead of mid-term election results.

"Some market participants suggest a strong chance of Republicans winning a House majority and a tight race for Senate control. We expect the USD-INR (Spot) to trade sideways and quote in the range of 81.30 and 81.80," Somaiya added.

Meanwhile, the dollar index, which gauges the greenback's strength against a basket of six currencies, rose 0.14 per cent to 110.70.

Global oil benchmark Brent crude futures advanced 0.03 per cent to USD 92.68 per barrel.

On the domestic equity market front, the 30-share BSE Sensex fell 419.85 points or 0.69 per cent to end at 60,613.70, while the broader NSE Nifty declined 128.80 points or 0.71 per cent to 18,028.20.

Foreign Institutional Investors (FIIs) remained net buyers in capital markets as they purchased shares worth Rs 386.83 crore on Wednesday, according to exchange data.