South Africa's new president aims to heal seismic splits within the governing African National Congress.
Motlanthe, 59, is known as "the elder brother" because of his calm and collected manner in even the most treacherous political waters.
His reputation as a bridge-builder will be tested as he fills the uncertain gap created by the ANC's decision to eject former president Thabo Mbeki, just months before the end of his term.
With elections due next year, Motlanthe must ease the divisions between supporters of Mbeki and the ANC's new leader Jacob Zuma - two rivals whose long-time feud was finally settled with Mbeki's forced departure last weekend.
Motlanthe has distanced himself and the party from near-hysterical calls by the party's youth league to spill blood and kill for Zuma.
In response to the militant language, Motlanthe recently said: "Of course there are individuals who are very angry... and who then make statements - this is not ANC policy."
"He has played a very smart bridge-building role," said Chris Landsberg, politics professor at the University of Johannesburg.
"He has been able to play a very detached role from the two camps... He was seen as neutral, as not balancing in favour of anybody."
Even the head of the opposition, Helen Zille, finds it hard to pick holes in Motlanthe's armour, calling him "perhaps the most level-headed and reasonable of all the politicians" in the ANC.
Known for keeping his personal life out of the public eye, an Ipsos Markinor survey in May found that around half of South African voters had never heard of Motlanthe or did not know enough about him to express an opinion.
Motlanthe is expected to serve until the general elections when Zuma is tipped to take office.
As Zuma has said he will serve one term, Motlanthe will be in pole position to return to the top job in the 2014 vote.
The bespectacled politician was born on July 19, 1949 into a working class family in the Johannesburg township of Alexandra, a hotbed of resistance to the apartheid regime.
He was a follower of the anti-apartheid activist and black consciousness leader Steve Biko, who died in police custody in 1977.
After 11 months in initial detention, Motlanthe was sent that same year to Robben Island, where democracy hero Nelson Mandela was also imprisoned, and was not released until 1987.
He gravitated towards the head of the ANC's labour unions wing throughout the 1990s.
The only stain on his record were allegations that he was mixed up in a global scandal surrounding the United Nations "oil-for-food" programme in Iraq - claims that in the end never led to charges.
When he was elected deputy ANC president last December, Motlanthe disarmed journalists by saying that rather than seek high office, he'd prefer to train the national football team as South Africa prepares to host the 2010 World Cup.
"Being president... No, please. Thank you," he said.
Those words now are a distant memory as Motlanthe becomes head of state - just a few months after he was appointed a minister without portfolio in Mbeki's cabinet.
But his tongue-in-cheek remark also illustrates the disarming qualities that could prove so vital as he seeks to heal political wounds left by the biggest shake-up since the fall of apartheid.
Taken from http://www.int.iol.co.za