Singapore Airlines has also frozen its intake of cadet pilots.
Singapore Airlines has asked its captains to volunteer for unpaid leave amid a global economic slowdown that has dented long-haul travel demand, the airline says.
The move came nearly a year after the company - considered a bellwether for the full-service airline industry - made a similar offer to its first officers.
The airline has also frozen its intake of cadet pilots as part of a slew of cost-cutting measures.
"Singapore Airlines (SIA) began offering voluntary no-pay leave to first officers in March last year and subsequently to captains who expressed interest," company spokesman Nicholas Ionides said.
SIA has "a temporary surplus of pilots and are managing it through this scheme, which is entirely voluntary", he said.
SIA has more than 2400 pilots - mostly captains and first officers.
The global financial crisis had led to excess capacity and slower growth than anticipated, Ionides said.
"This voluntary scheme will enable us to address the short-term surplus, while at the same time provide staff with the opportunity to take leave for personal reasons should they wish to do so," Ionides said.
SIA saw its net profit in the first-half of the fiscal year ending March fall by 30 per cent year-on-year, weighed down by high fuel prices and weak demand in the travel and cargo markets.
This followed a 69 per cent plunge in net profit in the carrier's financial year ended March 2012.