A billionaire investor in a Silicon Valley venture capital firm is set to testify for a second day in a high-profile sex discrimination lawsuit that has accused the firm of being an all-boys club where women were denied chances to advance and treated as second-class citizens.

John Doerr, a partner at Kleiner Perkins Caufield & Byers, will again take the stand Wednesday in San Francisco Superior Court in the lawsuit brought by his former chief of staff, Ellen Pao, who says she was denied a promotion because she is a woman and was fired in 2012 after she complained and filed her lawsuit.

The case has sparked debate over the treatment of women in the high-tech and venture capital fields, which are dominated by men.

“I don’t consider Kleiner Perkins to be a firm run by men,” Doerr said Tuesday under questioning by Pao’s attorney, Alan Exelrod. “We have many female partners.”

Doerr is among the most prominent venture capitalists in Silicon Valley in part for helping direct early investments in Amazon.com and Google after joining Kleiner Perkins in 1980. He sits on Google’s board and served on boards that advised President Barack Obama about economic policy. His net worth is estimated at $3.5 billion by Forbes.

Doerr appeared exasperated at times during hours of questioning by Exelrod, averting his gaze and shifting in his seat.

Exelrod has argued that Kleiner Perkins had a male-dominated culture where his client received a book of erotic poetry from a male senior partner and experienced retaliation by a male colleague after she broke off an affair with him.

Asked about the book of poetry, Doerr said Pao did not tell him the nature of the book during a 2007 meeting and did not seem upset by it. She was emphatic that her affair with the male colleague was in the past and not a problem, he said.

Doerr said he did not recall telling an investigator that Kleiner Perkins was run by men and that Pao had a “female chip” on her shoulder. The investigator had been brought in by the firm and looked into Pao’s complaint alleging gender discrimination and a complaint filed by a female employee who claimed she was sexually harassed. The investigator alleged that Doerr had made those statements.

Pao initially worked as Doerr’s chief of staff, writing his letters and speeches, among other duties, before becoming a junior partner in 2010 with full-time investment duties. The firm has denied wrongdoing and says Pao, 45, didn’t get along with her colleagues — a requirement for the junior partner position — and performed poorly in that role.

In a job review presented in court Tuesday, Doerr said Pao needed to improve her interpersonal skills and not be dismissive of peers who don’t meet her expectations, though he otherwise praised her performance in her first year as his chief of staff.

“People need to be able to confront disagreements on ideas and then agree and pull together as a team,” Doerr said under questioning by Kleiner Perkins attorney Lynne Hermle. “Ellen lacked those skills.”

Venture capital firms, which provide much of the startup funds for tech companies, have a reputation as being even more insular and male-dominated than the companies they help launch.

Women hold 15 to 20 percent of the technology jobs at tech giants Google, Apple, Facebook and Yahoo, according to disclosures by the companies.

Venture capital firms are even more slanted toward men. A study released last year by Babson College in Massachusetts found that women filled just 6 percent of the partner-level positions at 139 venture capital firms in 2013, down from 10 percent in 1999.

During questioning by Hermle, Doerr said he tried to increase the number of women in venture capital and the technology sector, including recruiting women and backing companies run by women.

“Almost always, women are better leaders than men,” he said.

Pao is seeking $16 million in damages. The firm is seeking to limit any possible damages by arguing that Pao is well-compensated in her current position as interim CEO of the popular social media company Reddit and hasn’t suffered financially since leaving Kleiner Perkins after filing her lawsuit.