By Lisa Baertlein

Starbucks Corp. will close 8,000 company-owned U.S. cafés for the afternoon on Tuesday, May 29, to train nearly 175,000 to prevent racial discrimination in its stores.

Starbucks’ roughly 6,000 licensed cafés will remain open. Starbucks said it would make training materials available to the employees of those stores, who are employed by the grocery stores or airports where they are located.

The announcement from the world’s biggest coffee company comes as it tries to cool tensions after the arrest of two African-American men at its Philadelphia café near upscale Rittenhouse Square last week sparked accusations of racial profiling at the chain.

The manager of the café called police claiming the two men had refused to make a purchase and had them arrested for trespassing when officers arrived. The two men told the manager they were waiting for a friend, who arrived as they were led away. The two men were later released without facing a charge.

The arrest sparked a strong reaction. Protesters in Philadelphia were joined by people on social media calling for a boycott of the company in what has become a major public relations test for Chief Executive Kevin Johnson.

Mr. Johnson, a former technology executive, took the helm about a year ago and is already fighting to boost traffic to company outlets amid intense competition from other coffee sellers, ranging from hipster cafés to fast food chains and convenience stores.

The afternoon hours are the slowest time for Starbucks’ business. Nevertheless, the closure of 8,000 stores and its corporate offices for an afternoon will almost certainly have an impact on sales. Starbucks did not say how many hours the stores would be shuttered on May 29.

“While this is not limited to Starbucks, we’re committed to being a part of the solution,” said Mr. Johnson, who has apologized for the “reprehensible” arrests of two African-American men and taken responsibility for the incident. The manager who called police no longer works at that café, according to the company.

Attorneys for the company said Mr. Johnson and the two men involved have “engaged in constructive discussions about this issue as well as what is happening in communities across the country.”

While Starbucks has deftly navigated thorny issues such as gay marriage, gun control and Congressional gridlock, race relations have proven more challenging.

Its 2015, the company’s “Race Together” campaign flopped. Designed to foster a conversation on the topic of race following the high-profile police shootings of unarmed African-American men, the campaign, instead, stirred an intense social media backlash.