China's Vice-President Xi Jinping has been named vice-chair of the powerful Central Military Commission, in a move widely seen as a boost to his likely succession of President Hu Jintao.
It comes on the last day of the ruling Communist Party's annual meeting.
Hu Jintao must retire as head of the party in 2012 and as president in 2013.
Mr Xi is following in the footsteps of Mr Hu, who was also promoted to the commission - which controls China's army - before becoming president.
Mr Xi was promoted by the Communist Party's Central Committee, a council of about 200 senior officials.
The 57-year-old will serve under Mr Hu, who is the current head of the commission, which oversees the 2.3m soldiers of the People's Liberation Army.
Appointment to the military commission and a parallel government role are seen as necessary preparations for the top post.
The BBC's Martin Patience in Beijing says the Communist Party tends to work out succession in advance to prevent power struggles among senior officials.
Mr Xi became a member of the Politburo Standing Committee - the ruling inner circle - in 2007 and was named China's vice-president the following year.
Seven of the nine current members of the committee are expected to stand down in 2012 because they will by then have served two terms.
That leaves Xi Jinping and Li Keqiang, who are widely seen as the country's leaders-in-waiting.
Mr Xi is the son of revolutionary veteran Xi Zhongxun, one of the Communist Party's founding fathers.
Known as a "princeling" because of his family lineage, Mr Xi's political ascension is owed in part to his family connections.
He is known as a plain-speaking advocate of business and a crusader against corruption among officials.
He is also married to a famous singer, Peng Liyuan.
News of his promotion followed the close of the meeting in Beijing, where social and economic plans for the next five years were also drawn up.
Instead of seeking a high rate of economic growth, China's leaders appear to want to close the gap between rich and poor and between coastal and inland areas.
Party leaders pledged to make "vigorous yet steady" reforms to keep the economy from faltering, state news agency Xinhua said, citing a document issued at the end of the meeting.
China wants to reduce the social divide in order to prevent disputes over pay and inequality which have led to unrest in the past.
The meeting came amid renewed scrutiny of human rights in China.
Just days before the plenum a letter signed by 23 Communist Party elders circulated calling for an end to restrictions on the freedom of speech.
A group of 100 activists in China also signed a petition calling for the release of jailed dissident Liu Xiaobo - a champion for democracy in China - who was awarded the Nobel Peace Prize.
Speculation that political reform would be on the agenda was sparked by Premier Wen Jiabao's recent calls for openness.
Mr Wen told US broadcaster CNN earlier this month that calls for "democracy and freedom [in China] will become irresistible".
But in a sign of possible resistance to those calls, China's state media did not report them domestically.