China on Thursday completed its once-in-a-decade leadership transition, naming, as expected, Xi Jinping, the 59-year-old son of a famed Communist revolutionary general, to the party’s top position, general secretary. He will also take over in March as the country’s president from outgoing leader Hu Jintao.

The transition ends months of internal rivalry, secrecy and speculation, and will determine the country’s future at a time of economic worries, increased regional tensions and widespread clamor for reform.

In a surprise, Hu also relinquished his title as chairman of the Central Military Commission, the body that runs China’s 2.3 million-member army. With Xi now taking over the chairmanship of the military body, China’s transition is now virtually complete, lessening the prospect of a lingering rivalry for influence between the outgoing and incoming leaders.

Xi, in his remarks, said the party’s trust and people’s expectations “are a source of tremendous encouragement for us, and put enormous responsibility on our shoulders.”

“The people’s desire for a better life is what we shall fight for,” Xi said. He said his main job was to “steadfastly take the road of prosperity for all.”

China’s new leadership team: The Politburo Standing Committee, which effectively runs the country, consists of mostly older, conservative establishment figures.

He said the ruling Communist Party would be “proud but not complacent, and we will never rest on our laurels.” He said the party suffered from problems of “corruption, taking bribes, being out of touch with the people, [and] undue emphasis on bureaucracy and formalities.”

What direction Xi and the other new leaders will take is not known. While waiting in the wings for five years, Xi has carefully avoided giving any hint of his priorities, remaining strictly neutral to avoid endangering his status as heir among the party’s competing factions.

Any changes to the system envisioned by Xi are likely to be constrained by several older party leaders considered more conservative in outlook who were named Thursday to the Politburo Standing Committee. The body effectively runs the country and was shrunk from nine to seven seats, ostensibly for faster decision making and greater ease for reaching consensus.

Xi and the other leaders, in look-alike dark suits and most of them wearing red neckties, walked onto a stage at the Great Hall of the People at 11:55 a.m., more than a half-hour later than expected. Xi introduced his new leadership team and spoke for about 10 minutes before they filed off the stage.

“Our journey ahead is long and arduous,” Xi said. “We must always be of one heart and mind with the people.”

Xi appeared relaxed and smiling, and he spoke casually as he read his speech, a major contrast to his predecessor, Hu, who often appeared stiff and formal in official gatherings and rarely looked up while reading his prepared text.

Those hoping this week-long party congress would send a clear signal in favor of openness and change were largely disappointed that the final Standing Committee lineup consists of mostly older, conservative establishment figures.

After Xi and the No. 2 official, Li Keqiang, who will become premier, the other top officials, in order of their new rank, are Zhang Dejiang, 66, a North Korean-trained economist now running Chongqing; Yu Zhengsheng, 67, the Shanghai party boss; and Liu Yunshan, 65, the head of the Communist Party’s propaganda department, which is in charge of censorship. The final two on the seven-member committee are Wang Qishan, 64, known for his economic management skills, who will be in charge of anti-corruption efforts as head of the party’s discipline commission in the new government; and Zhang Gaoli, 66, the party boss in Tianjin.

Left out from the final lineup were two one-time contenders most associated with reform: Wang Yang, the party chief in southern Guangdong province; and Li Yuanchao, the former party head in Jiangsu province and the head of the party’s Organization Department, in charge of staffing.

With Wang and Li both out, “a lot of people will be disappointed and see no reform hope for the future,” said Zhang Lifan, a historian with links to some of the leaders. With the way things are going, Zhang noted, “some people who were originally holding off going abroad to immigrate may even start their plans sooner.”

The age of the new Standing Committee members, mostly in their late 60s, virtually ensures that there will be another partial transition in five years time.

The transition is not likely to dramatically change China’s relations with the United States. Xi was long known as the heir apparent, and the Obama administration has been cultivating ties with him, including sending Vice President Biden on a lengthy trip here last year during which Xi played host in Beijing and in Sichuan province. Xi made a reciprocal trip to the United States this year with Biden as his host, and they attended a Los Angeles Lakers basketball game.

But in coming months, as Xi consolidates his power, bilateral military tensions are likely to remain high, as the United States continues its policy of rebalancing toward the Asia-Pacific and shoring up its alliances with countries surrounding China. Defense Secretary Leon E. Panetta is on a week-long trip that will take him to Thailand, Cambodia and Australia, where the United States has been expanding military cooperation and establishing a base in the northern coastal city of Darwin.

And this month, President Obama will travel to Cambodia, Thailand and Burma, the latter stop having symbolical significance as the United States and China are seen as rivals for influence in that strategically located Southeast Asian country.

The leadership transition is China’s first in a decade and only its second without chaos or bloodshed. The first real orderly transition was in 2002, when Jiang Zemin stepped down in favor of Hu.

One thing made clear amid the past week of ceremonial pomp here in Beijing is how thoroughly the aging Jiang has continued to dominate China’s leadership, appearing publicly at the opening of the congress and pushing his allies into key positions at the expense of Hu and other party grandees.

Wang Juan, Zhang Jie and Liu Liu contributed to this report.