The BSE Sensex climbed 0.6 percent early on Tuesday, led by export-driven software services companies as a weak rupee boosted their earnings outlook from foreign exchange gains.
The rupee weakened to its weakest level in two years as worries over Europe's debt crisis deepened after Standard & Poor's cut Italy's rating.
Tata Consultancy Services was up 1.5 percent and Infosys rallied 1.9 percent.
At 9:17 a.m. (0347 GMT), the 30-share BSE index was up 0.64 percent at 16,849.82 with 25 of its components gaining.
The broader 50-share NSE index was up 0.59 percent at 5,061.75.