The Argentinian writer Tomás Eloy Martínez, who has died aged 75 of cancer, was one of the most innovative journalists and novelists of his generation. He belonged to the group of writers who renewed Argentinian journalism in the early 1970s, challenging authority as well as freeing it from old-fashioned rhetorical formulas. Forced into exile after the 1976 military coup, Eloy ­Martínez took his skills to Venezuela, where he founded a groundbreaking newspaper. He later published several highly regarded novels, and helped the writer Gabriel García Márquez set up the Foundation for New Journalism in Colombia, which has been training ­hundreds of young Latin American ­journalists since 1995.

Born in the northern city of Tucumán, Eloy Martínez soon found his way to the capital, Buenos Aires. There he became the film critic for the daily La Nación and, in the 1960s, worked for the influential magazine Primera Plana. His front-page celebration of García Márquez's novel One Hundred Years of Solitude helped bring about its author's huge international success and led to a flourishing of Latin American writing.

In 1971 Eloy Martínez became part of the team led by the formidable editor Jacobo Timerman that created La Opinión, a daily newspaper that chronicled Argentina's descent into political chaos in the mid-70s. As editor of the ­influential cultural section, Eloy ­Martínez launched the careers of many new Argentinian writers, who appreciated both his generosity and his passion for debate and storytelling. During this period, he wrote La Pasión Según Trelew (The Passion According to Trelew, 1974) on the massacre of leftwing prisoners at a jail in the south of Argentina. His ­combination of testimony and real material with fictional elements led him to be described as the Argentinian Truman Capote, and provided him with a formula he was to return to in his later, more famous novels.

In 1970s Argentina, writing of this kind could have drastic ­consequences. La Opinión was shut down by the military authorities who seized power in 1976, and Eloy Martínez was forced to leave the country. He eventually ­established himself in the Venezuelan capital, Caracas. His third marriage was to the Venezuelan journalist Susana Rotker, and he helped renovate Venezuelan journalism by attracting new young writers to a newspaper he launched in 1979, El Diario de Caracas.

In 1984 he moved to the US, where he lived initially in ­Washington and taught at the University of Maryland. In 1985 his first internationally successful novel, La Novela de Perón (The Perón Novel), was published. Eloy Martínez had met Juan Perón often while the Argentinian leader was in exile in Madrid. In his novel, he combines historical fact with imagined accounts of how these events came about. He said about the book: "When I write journalism, every word is true. But when I say 'this text is a novel', nobody should believe a word of what's written there."

A decade later, in 1995, he continued to explore the history and myths of Peronism in a novel about Perón's wife Evita. In the novel, Santa Evita (Saint Evita), it is her corpse that is the focus of attention, illustrating the Argentinian obsession with dead heroes. This proved to be his most successful novel and has been translated into some 30 languages.

In the late 1990s, he returned to teach in the US. He was a distinguished ­professor and director of the Latin American studies programme at ­Rutgers University in New Jersey, but also ­travelled widely, giving conferences and continuing to help set up newspapers in Mexico and back in Argentina.

The last years of Eloy ­Martínez's life were marked by illness and personal tragedy. In December 2000, Susana was killed by a truck in New Jersey. Tomás was standing beside her, but suffered only minor injuries. Soon afterwards, he was diagnosed with cancer and was told that it had spread throughout his body. His illness made him only more determined to live each day to the full, and at times he seemed to have even more energy than before.

After his wife's death, Eloy Martínez spent more time in Buenos Aires, finally returning to live there in 2006, and ­marrying for a fourth time. His return to the Argentinian capital was also marked by the publication of two novels, El Vuelo de la Reina (Flight of the Queen, 2002) and El Cantor de Tango (The Tango Singer, 2004). The latter deals with the economic and political chaos that saw Argentina have five presidents in three weeks during the 2001 crisis.

The last time I saw Eloy Martínez was at the annual Buenos Aires book fair in 2005. No friend of what he saw as the authoritarian Peronism represented by the then president Nestor Kirchner, he publicly castigated Kirchner for not bothering to open the fair, insisting: "Books, not swords, were what founded Argentina."

Eloy Martínez is survived by four children, Tomás, Gonzalo, Ezequiel and Paula, from his first marriage; two children, Blas and Javier, from a relationship with Blanca Goncalves; and a daughter, Sol-Ana, from his second marriage. He also leaves 12 grandchildren.

• Tomás Eloy Martínez, writer, born 16 July 1934; died 31 January 2010