NAIROBI, Kenya, Dec. 29 — Kenya's septuagenarian leader, who has been involved in politics since independence in 1963, is being replaced by a septuagenarian leader who has been involved in politics since independence.

Still, the switch from Daniel arap Moi, 78, who ruled Kenya for 24 years, to Mwai Kibaki, 71, who has been elected to replace him, is being viewed as a far-reaching transformation of this East African country's political landscape. Advertisement

For although the two men may appear similar in some important ways, rising from humble beginnings to the nation's highest office, what they represent is markedly different.

Mr. Moi is one of the last of Africa's "big men," authoritarian rulers for whom the continent has become known. He turned Kenya's presidency into own personal office. What he uttered became the law of the land. His name is on everything from roads to currency — although Moi Avenue has big potholes just like all the other roadways, and the shilling notes that bear Mr. Moi's face are worth less than ever.

Mr. Kibaki grew up in the same political culture as Mr. Moi and spent years defending him. But when Mr. Moi was pressed by Western governments in 1991 to abolish one-party rule and open elections to the opposition, Mr. Kibaki jumped ship. He denounced the corruption in Mr. Moi's government, and has spent the last decade in opposition to the ruling Kenya African National Union.

Both the departing president and his successor spent most of their adult lives in the governing party, universally known as KANU, where treachery, corruption and malfeasance were in no short supply.

Mr. Moi served as vice president to Jomo Kenyatta, the patriarch of Kenya's independence and its first president. Upon Mr. Kenyatta's death in 1978, Mr. Moi took over the presidency, and the party leadership.

For his part, Mr. Kibaki helped draft KANU's constitution in the days before the break from British rule. He later served as finance minister to Mr. Kenyatta and as Mr. Moi's vice president, a position he was later fired from after a power struggle. Even then, he stuck by his leader and his party.

Until his last days in KANU, Mr. Kibaki defended the party as the best way to develop Kenya. He sought to reform KANU from inside, and denounced as agitators those who tried to discredit it. Over the last decade, he has been singing a new tune as Kenya politics has opened up to the extent that one could openly criticize the president and his party without landing in prison — and now even vote it out of office.

The social aspects of politics are not his forte. His official biography says that one of his weaknesses is that he is regarded as aloof by ordinary Kenyans. Some longtime friends say the same about him.

"He was not very social and did not want to go out with his friends," recalled Herman Wahatha, 74, who went to high school with Mr. Kibaki. "When he was not herding cattle, he was either studying or working on his hobby." That was before golf became his passion. What he liked to do as a youth, Mr. Wahatha said, was to sharpen sticks to make traps that he would use to catch moles and other rodents.

The new president was born in 1931 in Othaya, near the peaks of Mount Kenya. He grew up in a mud hut herding the family's cows. At Nyeri Boys School, he slept on a timber board and hay mattress, which he jokes is the reason he still tends to stand up straight.

For now, though, he is sitting, in a wheelchair, recovering from injuries he suffered in a car accident during the campaign. If anyone suggests that Mr. Kibaki's age is an impediment, his backers compare him with Nelson Mandela, who led South Africa in his 70's.

Mr. Kibaki is married to Lucy Muthoni and has four grown children and three grandchildren. He loves golf (yet he has a 28 handicap) and jazz music, and prefers his beer the way most Kenyans do — warm. He began his political activism at Makerere University in Uganda, which was the finest place to study in colonial East Africa, as chairman of the Kenya Students Association and vice chairman of the Makerere Students Guild.

He later went on to the London School of Economics and it was while he was there that one of his brothers was killed in the guerrilla struggle toward independence, known among some as the Mau Mau emergency.

Mr. Kibaki, who has always been the cerebral sort, did not join in the fighting himself, but he and other young nationalists did sit in a bar one day and draft the constitution over drinks for the new KANU party.

With the announcement that he would become president, Mr. Kibaki has dislodged the party from power. Those who have known him over the years are now watching and waiting for his next transformation.

"Kibaki was Moi's vice president for 10 years and he didn't seem to think he was such a bad guy in those days," said Smith Hempstone, the United States ambassador to Kenya in the early 1990's, when Mr. Kibaki was still a top KANU man. "He did have a reputation for being smart and we'll have to see."