As it hunts for ghosts, NBC Universal’s Sci Fi Channel is scaring up larger numbers of female viewers.

“Ghost Hunters,” now in its fourth year on Sci Fi, is helping the male-skewing network achieve its goal of balancing its demographics.

As a genre, science fiction tends to attract more males than females. That’s reflected in the audience for Sci Fi Channel, which is about 56% male. Sci Fi’s most heralded show, “Battlestar Galactica,” attracts an audience that is 65% male and 35% female.

Since most of television skews toward female viewership, the handful of networks that attract a greater proportion of men—ESPN and History, for example—try to take advantage of their unique audience to sell ads to marketers in categories looking to reach males, such as financial services, insurance and video games.

But Sci Fi, a top-10 cable network trying to shake the perception of its fans being Trekkies who live in their parents’ basements, opted instead to reach out to female viewers.

“We have that debate every year with the advertising team,” said Dave Howe, president of the Sci Fi Channel. The network came to the conclusion that it wanted the largest total number of adult viewers, and decided to work toward a 50-50 split between men and women.

“We see this as the way to maximize your revenue,” he said.

“Most of the dollars out there are chasing either women or adults,” said Carrie Drinkwater, senior VP and director of national broadcasting at media buyer MPG.

Mr. Howe said the network maintains critical mass with both males and females. But, he added, “Companies in the pharmaceutical and packaged-goods industries have chosen to advertise on the network because of what ‘Ghost Hunters’ is doing.”

In its fourth year, “Ghost Hunters’” viewership is up 31% from a year ago, and that audience is 56% female.

“The reality programming is absolutely driving their female numbers,” said Nicole Romanik, VP and account director for national broadcast at Initiative. And even though it’s a male-skewing network, it’s already got nearly as many female viewers during prime time as VH1 and HGTV, she noted.

“That’s not exactly what you’d expect,” Ms. Romanik said.

Not all of Sci Fi’s attempts to appeal to female viewers have resulted in successful shows for the networks.

Reality shows, for example, tend to skew female. And women tend to have an interest in the paranormal. But when Sci Fi aired a show called “Psychic at Large,” it attracted women, as one would expect, but it drew practically no men, so it was a failure.

What Sci Fi learned from that effort was that while women tend to believe in the paranormal and the afterlife, men need such subject matter to at least attempt to provide some sort of scientific testing to appeal to their rational side.

So when the “Ghost Hunters” use gadgets and gizmos to try to document the presence of spirits, that “gives it credibility from a male point of view,” Mr. Howe said.

Sci Fi has been adding more shows to its schedule in the paranormal genre that attract female viewers, including “Ghost Hunters International” and “Destination Truth.” It also ordered new series “Ghost Hunters: College Edition” and “RelicQuest.”

It’s important that the shows fit into the network’s lineup, Mr. Howe said. Through scheduling and promotion, Sci Fi hopes its new female viewers will watch other shows on the networks.

“We’re not interested in any islands in the schedule,” Mr. Howe said.

Despite the influx of new shows and female viewers, Sci Fi will retain its geek chic.

“I think the Trekkies of the world are always going to watch Sci Fi,” Ms. Romanik said.