Google Inc shook off the economic doldrums to deliver a third-quarter profit that topped analysts' expectations, supporting the internet search leader's theory that its advertising system will prosper even in tough times.

The Mountain View, California-based company said Thursday that it made $US1.35 billion ($A2.08 billion), $4.24 per share. The profit rose 26 per cent from $US1.07 billion ($A1.65 billion), or $3.38 per share, at the same time last year.

Excluding costs for employee stock compensation, Google said it would have made $4.92 per share. That figure surpassed the average estimate of $4.75 per share among analysts polled by Thomson Reuters.

Revenue climbed 31 per cent to $US5.54 billion ($A8.52 billion). After subtracting advertising commissions, Google's revenue totalled $US4.04 billion ($A6.21 billion) - about $US20 million ($A30.75 million) below analyst estimates.

Analysts had been decreasing their projections amid cascading waves of investor pessimism that pounded Google's stock price to a three-year low of $309.44 earlier Thursday. The shares subsequently rebounded with the rest of the market later in the day to close at $353.02, up $13.85, and then surged by another $40.98, or 11.6 per cent, in extended trading after the company released its third-quarter results.