Analysts are divided over what the European Central Bank's governing council will agree when it meets later in the day. Some say it will keep interest rates unchanged and not approve more stimulus measures in an effort to spur governments to take action themselves, such as closer fiscal ties and the creation of a banking union.
Other experts, however, predict the central bank will cut interest rates below its record low of 1 percent to help growth or at least indicate it will do so next month.
"Much in terms of market direction today will hinge on the outcome of the ECB meeting and press conference," said Mitul Kotecha, an analyst at Credit Agricole CIB who expects a quarter-point rate cut.
The FTSE 100 in Britain, where markets were closed Monday and Tuesday for Jubilee celebrations, gained 1.4 percent to 5,338.34 by late morning. Germany's DAX rose 1.7 percent to 6,072.58 and France's CAC-40 gained 2.1 percent to 3,049.57.
Investors were also hoping that the Federal Reserve might sanction a new round of monetary stimulus, or "quantitative easing", in which the Fed buys Treasury bonds to drive interest rates lower, after economic indicators turned sharply lower in recent weeks.
Although a survey of the U.S. services sector showed a timid improvement on Tuesday, data on jobs growth and manufacturing last week signaled a sharp slowdown in the world's largest economy. The market hope is that the evidence is now strong enough for the Fed to take action.
Official data confirmed that the eurozone economy did not contract in the first quarter. A revised estimate of earlier released figures showed the currency union's economy stagnated, avoiding a technical recession, but offering little hope of any recovery.
After gains in Asia, Wall Street also appeared set to rise on the open, with Dow Jones industrial futures up 0.9 percent to 12,229 and S&P 500 futures adding 1.1 percent to 1,298.80.
Later in the day, traders will eye the U.S. Federal Reserve's so-called Beige Book, a survey of businesses across the United States and monitor Europe's debt crisis developments, in particularly any progress in fixing Spain's banking crisis.
Spain needs money to rescue ailing banks, but can currently only receive such aid from the EU in a government bailout package. Madrid adamantly wants to avoid such a solution, as it would mean fellow eurozone countries and the International Monetary Fund would be allowed to impose fiscal policies on the country.
The country's government would like to allow the EU bailout fund to give money directly to the banks. Several other countries support that option, as well as the European Commission and the European Central Bank, who are expected to propose such a measure at a summit on June 28.
The lingering concern, however, is that creating banking union with the power to bail out banks directly still faces the opposition of Germany and would take months, if not years, to become fully operational, as it would have to be approved by national parliaments throughout the eurozone.
While Spain's borrowing rates edged down on Wednesday, to 6.23 percent, they remain uncomfortably high, indicating investors are still worried about the country's financial future.
In Asia, Japan's Nikkei 225 rose 1.8 percent to close at 8,533.53. Hong Kong's Hang Seng added 1.4 percent to 18,520.53. Australia's S&P/ASX 200 edged 0.3 percent up to 4,055.30, still buoyed by the Reserve Bank of Australia's decision Tuesday to cut interest rates by a quarter percentage point.
Markets in Singapore, Indonesia and Taiwan also moved higher, but those in mainland China fell. Markets in South Korea were closed for a public holiday.
Benchmark oil for July delivery was up 88 cents to $85.17 per barrel in electronic trading on the New York Mercantile Exchange. The contract rose 31 cents to settle at $84.29 in New York on Tuesday.
In currencies, the euro rose to $1.2496 from $1.2446 late Tuesday in New York. The dollar rose to 79.12 yen from 78.73 yen.