How can I convince my manager who loves SVN to let me start our new project on Git?

For our projects, we use SVN or GIT, depending on the team. If you are the only dev on the project, the case is easier. But if there are other devs on the project who also use svn, it may be tough. If it is a startup project, and time is tight, and your manager has a gazillion things to take care of, your manager really should stick with SVN, having you learn SVN. [rather easy] If it is a project wherein most new devs may only know SVN [i.e. .NET project], the manager should stick with SVN, again. You should talk to your manager and look at things from his perspective. Make the best decision for the project, not based on your personal love of a technology.

Create an example, both in a git repo and a svn repo, where you both work on branch (or a branch of a branch), create a conflict and ask him to resort it. Hopefully, the pain it will take him in SVN versus the ease of GIT would prove your point. Further, if applicable to your work environment/project, you could demo the distributed fun of git, like pulling directly from a co-worker's repo (as appose to working on a single master repo). As a last resort, if that doesn't work, I know of people who have worked on their own local git repo's for branching/merging/revisioning/general development and when ready, pushed their result to the company's svn repo. (worse case if you can't get the entire project on board the git ship)

I agree with the suggestions about just using git yourself, along with git-svn. Obviously, you won't necessarily get the full benefits (sharing with git peers via git should probably be avoided unless one of you becomes the SVN committer). I have used a git repo nested within a ClearCase workspace before and pushed into ClearCase when I was done. Admittedly, I didn't have to worry about incoming rebases in my case. If I did need to, I'd keep a branch synced with ClearCase, then rebase my work in progress onto that branch after rebasing with ClearCase.

As someone who uses both and is working in a mixed git/svn shop I'd have to side with your manager.  The hassles using two separate systems don't outweigh the benefits.  Having said that since your question asked how to convince your boss to use GIT I would play up the fact that you can access svn repos within git so you could technically test the waters without really fully moving to git (as a starting point) then when that goes well use the argument that "we're pretty much using git anyway".  It might also help to get other people in your department on board as well.

You don't need to convice your manager to use git, you can let him use SVN and you can use the git-svn bridge, or version your project with both tools, you can combine git that way thanks to distributed nature of git

Don't you think "love" might be a bit strong? It's just version-control software! Yes, git is fast and powerful and can be satisfying to use, especially for people with librarian impulses and control freaks, but let's keep things in perspective. Presumably, the goal here is collaborating with others to achieve some goal unrelated to version control. Why don't you start out with the repository in Subversion, but with you using git-svn to access it? That way you (personally) will get many of the benefits of distributed version control, while keeping the canonical version history in a centralized (Subversion) repository that makes your boss happy. If that goes well, and it should, eventually you can set up a parallel public Git repository and more of the team can start to use it -- while still pushing and pulling to the authoritative Subversion repository. Eventually, you can transition the authoritative repository to be Git as well after you bring your boss on board. But you don't have to do it all at once. You can go person by person and do it gradually, bringing your boss over as the last step. Keep in mind that Git does not necessarily provide all the features of centralized version control. For example, with Subversion there is one canonical timestamp on every commit, which represents both the time the commit was made and the time it was "pushed" to the repository, taken by the same clock that marks all the other commits. By contrast, with Git every commit has its own unauthoritative timestamp provided by the clock on the machine where it was made. Commits can be altered after the timestamp is set (e.g. by amending or rebasing). And Git has no accessible record of when commits were pushed. (Repositories do not export a reflog.) So in other words, if you want to answer the question, "If you did a checkout from our repository on date x, what was the code you got?", that is a question Subversion can answer. Git itself cannot currently answer such questions because so far there is no way to retrieve the target of a ref in a remote repository as of a particular moment in the past. Your boss might well have some reasons to be wary of distributed version control if that is a question you need to answer, e.g. for regulatory reasons or because you use VCS refs as a record of what is in operation.