Portrait of the martyr as a young man

Ian Thomson charts Che's progress from playboy to executioner; Che Guevara: A Revolutionary Life by Jon Lee Anderson, Bantam Press, pounds 25

In the 1960s Che Guevara's bearded face appeared on more student bedsit walls than damp stains or Jimi Hendrix. The famous photograph of saintly eyes and straggly black hair was taken in Havana 14 months after the Revolution. It was March 1960. Che had been standing on a balcony, half obscured by Castro's bulk, when he moved into a journalist's lens. An Argentine of Spanish ancestry, Che became an icon in the West like Warhol's Monroe. Cubans nicknamed him Che - "mate" - after his comradely leadership.

Ernesto Guevara (de la Serna) devoted 11 years of his brief life to Fidel's Revolution. Even in death there was a sainted air to his appearance. After he was executed by the military in a remote Bolivian schoolroom on 9 October 1967, the nurse who washed Che's corpse and the nuns at the hospital where his body was displayed kept locks of his hair. They said he resembled Jesus Christ. The Bolivian High Command wanted to obliterate every trace of the freedom fighter: before two days were out, all that remained to be seen of him were his severed hands, stoppered in formaldehyde for fingerprint identification.

The location of Che's grave in Bolivia was revealed by Jon Lee Anderson in 1995 during his research for this diligent biography. Anderson is a Time magazine journalist and his determination to interview all who knew Che is admirable. He spoke to Che's widow, Aleida March; to the rebel's final interrogator, the CIA stooge Felix Rodrguez (who embraced Che after communicating his death sentence), and to the Bolivian army sergeant who volunteered to execute him. Disguising his identity from Fidel's assassins with a variety of wigs, Mario Tern repeats Che's last words: "I know you've come to kill me. Shoot, coward, you are only going to kill a man."

Thirty years after his death, Che Guevara: A Revolutionary Life gives an admirably balanced account of the Argentine adventurer, his real achievements and glamorous Robin Hood appeal.

Obsessed with finding a cure for his chronic asthma, Guevara took a medical degree at Buenos Aires in 1953. He wanted to remedy the social injustice of South America - at first with preventative medicine, later through armed insurrection.

Che could be ruthless. During the long guerilla war in Cuba, he personally killed the first traitor of the revolution. "I ended the problem by giving him a shot with a .32 pistol in the right side of his brain ..." Still unpublished, Che's private diary reveals a chilling detachment from violence. In 1959, after Fidel's victory, Guevara oversaw an estimated 550 executions in Havana. Che's father, an Argentine tea planter, remarked that "Ernesto had brutalised his own sensitivities".

It was not always so. In 1952 Guevara had travelled round South America on a motorbike, gallivanting like a beatnik down Peru's desert Pacific coast and up to the ruins of Macchu Picchu and staying as a guest of the President of Ecuador. A middle-class Argentine with little interest in politics, then he preferred to sleep with the family maids.

As a doctor in the backwoods of Guatemala three years later, Guevara was introduced to leftists opposed to the regime funded by United Fruit - the company which had made of neighbouring Honduras the original "banana republic". This was a crucial encounter, encouraging Guevara's loathing for Uncle Sam and his eventual conversion to Marxism.

Guevara was the only non-Cuban aboard the Granma, the cabin cruiser that ferried 82 revolutionary patriots, led by Fidel, from Mexico to Cuba in 1956. The Cuban revolution was not communist but nationalist in inspiration. After Batista's thuggish regime had been overthrown and Che made director of the Cuban national bank, he retained his combat fatigues and black beret, mindful of his proletarian image. He was a very different revolutionary to the Fidelistas. While Castro was the paunchy epicure with a relish for pasta con vongole, in later years Che didn't dance or drink.

His passion was for chess and mathematics. A literate man, he had an acidic sense of humour and the adventurer's contempt for bureaucracy. Unhappy with the course of Fidel's reforms - too much paperwork - Che left Cuba in 1965 to champion other revolutionary causes in Zaire and Bolivia.

Anderson proves conclusively that Fidel sent Che Guevara (already the father of five children) to Bolivia in the spring of 1966. The decision eventually led to Che's death at the age of 39 during a half-baked guerilla insurrection.

Tied up like an animal in the Bolivian schoolroom, Che was didactic to the end. Motioning to a grammatical error on the blackboard, he told a frightened teacher that her school was a disgrace. If the rest of Che's life was a glamorous failure, he had at least helped to eradicate Cuba's illiteracy.

Occasionally Anderson's prose is clumsy ("Buenos Aires now had a melting pot's combustive, passionate quality") and he quotes too liberally from Che's own guerilla manuals, which are not scintillating. But Che Guevara: A Revolutionary Life is an excellent guide to the myth behind the martyr.

Were he alive today, Ernesto Guevara de la Serna would be approaching 70. He died with his boots on, caught in full stride as he would have wanted.

Che Guevara: A Revolutionary Life, by Jon Lee Anderson is published by Bantam Press at pounds 25.