The Illinois Democrat's travels in 2005 and 2006 cost U.S. taxpayers nearly $28,000 (EUR 21,000) as he studied nuclear proliferation, AIDS, Middle Eastern violence and more.
Eight other new senators took office in 2005, and about $19,200 (EUR 14,700) was the most anyone spent for government-paid travel, according to reports filed with the Senate Office of Public Records.
Obama's journeys are unusual for such a junior senator, but not for someone thinking of a presidential run. Obama has announced his candidacy for president in the 2008 election.
"Valuable or not, it's the thing they all do to show that they're knowledgeable about the world," said Stephen Hess, a George Washington University professor and former presidential aide.
Obama was one of two first-term members of the Senate Foreign Relations Committee in the 109th Congress. He spent $18,822 (EUR 14,388) in per diem and transportation costs in 2006 as he visited Middle East hotspots and toured Africa. The previous year he spent $8,313 (EUR 6,355) visiting the former Soviet Union and the United Kingdom.
The first-term senator with the next greatest spending on taxpayer-funded trips was Senator Richard Burr, a North Carolina Republican whose visits included China, Russia and the Middle East at a cost of about $19,200 (EUR 14,677). Ranking third was Senator Tom Coburn, an Oklahoma Republican who spent $17,867 (EUR 13,658) to visit China and Kuwait, among other places. Neither is a member of the Foreign Relations Committee.
However, other first-term senators also took trips - both foreign and domestic - funded by private groups, which Obama does not accept. Ethics watchdog groups are critical of privately funded travel, arguing that it serves mostly to ingratiate lawmakers to their sponsors, who often are lobbying them on government policy. If Coburn's privately funded trips are included, his total travel amounts to nearly $29,000 (EUR 22,000) for the two years, more than any other first-term member.
Obama's travels were also eclipsed by some of the committee's more senior senators.
Democratic Senator John Kerry, for instance, spent more than $61,000 (EUR 46,000) on just taxpayer-subsidized trips during 2005-2006. Senator Richard Lugar, the Republican who was then chairman of the committee, spent more than $94,000 (EUR 71,000) in combined taxpayer- and privately funded trips.
Obama's staff issued a brief statement saying he is proud that his Russia trip led to an anti-proliferation law and that his Africa trip encouraged people to be tested for AIDS. Staff members also released a letter from Lugar praising Obama's personal diplomacy on the African trip.
Before he went to Africa, Obama told The Associated Press that the trip held "symbolic power" because he is the only black U.S. senator.
"What a trip like this does is it allows me to really target a wide range of issues that come up on the international stage and help Americans appreciate how much our fates are linked with the African continent," Obama said at the time.
The official travel spending figures reported to the government do not include the cost of flights on military aircraft, which are often used on overseas trips by a congressional delegation. They also omit the staff time and security costs incurred by the U.S. embassies in the countries lawmakers visit.
Senators often bring along aides at additional expense to taxpayers. Obama took his foreign policy adviser and communications director to the former Soviet Union at a cost of $18,576 (EUR 14,200). On the African trip, he took two aides, spending about $6,000 (EUR 4,600) in campaign funds to offset the cost of one.
Obama's trips clearly are not junkets and could educate him about important issues while strengthening his presidential resume, Hess said.
In Africa, Obama was often treated like royalty. Adoring crowds showed up wherever he went in Kenya, the home of his father.
Obama met several times with AIDS researchers and activists, and he and his wife publicly took an AIDS test to encourage Kenyans to do the same. He caused a stir by speaking out against corruption and the corrosive role of tribal loyalties in the Kenyan government. He also met with African presidents and activists, and traveled to remote villages, refugee camps and U.S. military posts.
And, Obama found time to take his family on a safari - something he did not bill to taxpayers, the AP says.
When Obama went to the Middle East, he met with Israel's foreign minister, spent two days in Iraq talking to officials and military commanders, and made stops in the Palestinian territory, Jordan and Kuwait.
During his trip to the former Soviet Union, Obama joined Lugar in touring dilapidated weapons factories in Ukraine, watching workers destroy explosives and visiting the site where a nuclear missile was being dismantled.