This is a drawing of the Ben and Julie kiss in that comic. Now I realize that this wasn't in the cartoon, but technically it is still their first visualized kiss. I don't know the name of the comic so don't ask me it. If you are dissapointed at the fact that it is in a comic book don't worry there is an episode of Ben 10 Ultimate Alien coming up called "the Perfect Girlfriend" that looks like is going to have Ben and Julie kiss in it. I'm not 100% sure they're going to in THAT episode, but it seems entirely possible.
Could some one please tell me the name of that comic that Ben and Julie kiss in so I can post it.[link]
Ben 10 belongs to Cartoon Network