Jean Helene, the Abidjan correspondent of French radio station Radio France Internationale, was shot dead in his car which was parked near the national police headquarters.
A police source said he was waiting to interview a group of opposition activists freed from police custody.
The police source said that an officer, thought to have fired the fatal shot, had been arrested and was being questioned at the police station to explain the circumstances of the shooting.
Police said Helene suffered a gunshot wound to his head and had been formally identified.
French President Jacques Chirac offered his condolences to Helene's family and urged the Ivorian authorities to launch an enquiry into the death, a spokeswoman in Paris said.
"He called on the Ivorian authorities to shed light on the facts around this killing which should be the subject of a full and immediate enquiry," said Elysee Palace spokeswoman Catherine Colonna.
According to a witness at the police station, an officer had come in and told his superior that a "white man was sitting in his car, making a telephone call, and said he was journalist.
"His boss told him to forget it, that the man was only waiting to interview the freed men, and the policeman went back out again."
Shortly afterwards he heard a shot being fired.
A witness heard a senior policemen telling his men to disarm one of their colleagues and bring him in
After leaving the police headquarters, the witness saw a red car parked nearby and as he approached he saw a body within lying in a pool of blood.
The witness, who requested anonymity, then heard a senior officer telling his men to disarm one of their colleagues and bring him in.
An autopsy would be carried out swiftly, the police source said.
Ivory Coast President Laurent Gbagbo, Prime Minister Seydou Diarra and Security Minister Martin Bleou, as well as the French ambassador Gildas Le Lidec, were quickly on the scene.
The Ivorian president made no official comment.
The journalist had arrived at the police headquarters to interview 11 activists of Ivory Coast's main opposition party, who had been released by the police after being detained for several days.
The arrests had been made in connection with an alleged assassination plot, the security minister said on Monday.
"Those concerned have been placed at the disposition of the competent services of the national police," Martin Bleou said in a statement.
The arrests had been made "in the context of information relative to a plan to assassinate political, administrative and military figures," Bleou added.
The Ivory Coast has been in crisis
since a military coup last Sept
Alphonse Kobenan Kossonou, a member of the political bureau of the Democratic Party of Ivory Coast (PDCI, formerly in power) was taken from his home in Abidjan on Thursday, Adou Kouame, a family friend, had told AFP.
Two armed men in civilian clothes came to the house and told him to follow them to the police station.
The Ivory Coast has been in crisis since last September when a military coup was launched against President Laurent Gbagbo.
Although a government of national reconciliation has been established the country is effectively cut in two with rebels controlling the north.
In February human rights bodies denounced the presence of a "death squad" operating in the area controlled by loyalists.