LOS ANGELES — Walter Mosley's latest book, "Killing Johnny Fry: A Sexistential Novel," was greeted by some of the worst, most hostile reviews of the writer's career. The critical savagery could be written off as a prudish reaction to a book that is more than a tad pornographic. Or it could be the result of Mosley's own missteps — a dirty book, after all, is a very delicate proposition, and not always easy to take seriously.

There might be a venerable tradition of literate porn, from the Marquis De Sade to Bret Easton Ellis, but there is also the annual Bad Sex in Fiction prize given by the Literary Review (last year's winner: Iain Hollingshead's "Twenty Something"). When it comes to the subject of sex, a writer's reputation is no inoculation against squirmy critical tittering and ridicule. Just ask Philip Roth, Norman Mailer, John Updike or, most recently, Jane Smiley.

The 53-year-old Mosley makes no apologies. He thinks the reaction is due not just to his having written what some people call pornography, but also to another literary taboo: writing honestly and directly about a certain kind of heterosexual male experience.

"A lot of people don't like this book," Mosley said at a recent Los Angeles Central Library Aloud series panel on the future of erotic fiction. "I wrote about how a heterosexual male feels having sex. In the first person, from the inside. It's almost never done."

And yet it's hardly a radical proposition. As his co-panelist, the gay writer John Rechy, explained, gay writers have been on this territory for so long, "I get a little piqued when a straight writer gets all this attention for it."

Later in the event, Mosley talked about the pressure on straight men to be quiet about their sexuality, or to talk about it only in the accepted ways. "I don't mind that. I understand," he kept saying, unconvincingly.

Why shouldn't he be a little irritated by it all? Mosley has long been a critic's darling, regularly called "a national treasure" for his soulful Easy Rawlins mysteries. He's a rare kind of crossover success story, a genre writer who gained a mainstream literary following and a black writer with an avid white readership. Even when he's ventured into other genres, such as science fiction in "The Wave" or political polemic in "What Next," he has felt the love; his less-than-rave reviews were at least respectful.

Make no mistake: Mosley shows no signs of slowing his prolific output.

"Killing Johnny Fry," released in February, is selling even better than expected, his publisher says. (BookScan numbers show it has sold a little more than 8,000 copies.)

This month, his next book — a straightforward, friendly guide for aspiring writers called "This Year You Write Your Novel" — is set to be published.

He also has managed a productive and relaxed relationship with Hollywood, working as an occasional story coach for screenwriters and fielding constant interest in adapting his books and other projects. The movie of his first Easy Rawlins novel, "Devil in a Blue Dress," with Denzel Washington and Don Cheadle, is considered by many to be among the best literary adaptations, and production on "Little Scarlet" for HBO, starring Mos Def and Jeffrey Wright, is scheduled to begin in the fall.

And yet "Killing Johnny Fry" does feel like a brave leap into the void for Mosley. The book tells the story of Cordell Carmel, an innocuous, sexually inhibited translator in New York whose world is rocked when he spies his girlfriend having sex with another man, a white guy; Cordell is black. He responds as any shocked contemporary cuckold would, by engaging with as many women as he can, in as many ways as he can imagine, and then romping through New York's sexual underworld.

Through it all Cordell confronts the anguish and emptiness of his previous life, ending up wiser, but not at all sure that he will ever come close to enlightenment.

"Killing Johnny Fry" got a few sympathetic reviews, but mostly it was a mocking and dismissive chorus. "This book made me want to cover my eyes, not from prurience but the excruciating embarrassment one can feel on other people's behalf," said a typical one. "Even more embarrassing than our hero's heroic potency are his flashes of insight," complained another.

A week after the library panel, Mosley, who lives in New York, was still in no mood to retreat from his critics.

"I think of a book like 'All Quiet on the Western Front,' " he said while having breakfast in Beverly Hills, bringing up Erich Remarque's famously unflinching novel about the horrors of World War I. "That book is unremitting violence from beginning to end. No one would think of saying, 'Look at this! It's just violence!'

"Sex is the same thing. What I was writing about was as common as rain. A guy having some extreme experiences in a midlife crisis."

His goal, he said, was specifically not to write "erotica": "For me I think it's really important to put it out there, to not be coy. To say, 'Well, this is what's happening.' Whereas erotica talks about urges and feelings. You refer to it and allude to it."

But there's also his male protagonist's physical and emotional vulnerability. "The writing should be able to tell you, 'How does it feel on the inside to be you?' " he said. "I think that's unusual for a straight man. Certainly not mainstream."

Mosley, Rechy said, is "a terrific writer," but "Killing Johnny Fry" "seemed to me to be doggedly sexual: 'Now I am going to write a sex novel.' " It's an occupational hazard for straight writers, he said, as they can ignore or take up their sexuality as they please: "It always reads too forced to me." Straight writers, he said, "have a way to go before this frank approach to sex can be integrated into a truly literary project."

In the meantime, Mosley is moving on. He doesn't have any plans to return to sex writing in the near future, "but you never know," he said. He has no regrets, he said, about telling the story he told, regardless of who was ready to hear it. "Truth is in language," he said, "and language has changed."