It is known that during Goblet of Fire, Cho Chang and Cedric Diggory date. They attended the Yule Ball together and during Order of the Pheonix Cho mentions how she'd been dating Cedric and they'd once went on a date the Madam Puddifoot's coffee shop in Hogsmeade. Madam Puddifoots is often filled with kissing couples so one can guess Cho and Cedric might have kissed there aswel, or some other time as they very muich loved each other. During the Triwizard Tournament's second task Cho was taken hostage as the ting Cedric would miss most.
Though it never mentions them kissing, it also doesn't say they didn't. However in Order of the Pheonix we witness Cho kissing Harry after Cedric's death.
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We don't know for sure but it is likely to have been Cedric Diggory.
Harry kisses Cho Chang and Ginny Weasly.
In the book he kisses Ginny in her room before being walked in on by Ron and Hermione. In the film he kisses Ginny in the Burrow kitchen before noticing that Fred is watching them :)
In the fifth book, Harry asked Cho out for a date in Hogsmeade. Harry was still adjusting his feelings for her, so when they had nothing to talk about Cho decided it was time to talk about Cedric. Harry changed the subject saying, "Let's not talk about Cedric now." That disappointed her, so she cried and left. A few days later, they made up.. But after a betrayal of Marietta Edgecombe, a friend of Cho's, Harry got mad once again. He retorted that she should choose more friends more wisely, and that 'a really nice girl who I didn't dream of her doing that(-Cho)' was plain stupid. They broke up once and for all.
The Day the first term ended that year Harry and the DA had a last meeting before the Christmas holidays. After that meeting Cho and Harry where left alone and they kissed for the first time. That night Harry had the vision of Nagini attacking Mr.Weasley. That was Harry's first kiss.