Kofi Annan has marked nine years since he brokered a deal for peace in Kenya after 2007/8 post-poll violence.
The peace accord signed between retired President Mwai Kibaki and Opposition leader Raila Odinga ended the violence that was sparked by a disputed election.
It saw the birth of the Grand Coalition Government with Kibaki as the President and Raila as the Prime Minister.
"Nine years ago today, during the violent political crisis in Kenya, Mwai Kibaki and Raila Odinga signed the National Accord and Reconciliation Act," Annan, who is
former UN Secretary General wrote on his Twitter page on Tuesday.
Annan described his chief mediator role as the most engaging but noted that it ended a stalemate that left at least 1,000 people dead.
"My role in mediating was amongst the most intensive and enduring of all my interventions," he said.
The former secretary general said several key elections in Africa have unfolded much more peacefully since "but we have a long way still to go".
"Every African must be able to trust in our political institutions, in the supremacy of the rule of law and in the accountability of our leaders," he said.
More than 600,000 people were rendered homeless by the violence.
Kibaki's PNU and Raila's ODM traded accusations of genocide in a standoff that shocked world leaders, who had long viewed Kenya as a peacemaker, rather than a problem, on a volatile continent.
Official results showed Kibaki narrowly won the election but Raila said victory was stolen from him by vote-rigging. International observers said the poll was flawed.
President Uhuru Kenyatta and DP William Ruto faced crimes against humanity charges at the ICC over the post-poll chaos. Uhuru was then deputy PM while Ruto was Eldoret North MP.
Their cases were dropped in 2014 and 2015 respectively for lack of sufficient evidence.