I'm an international student and graduating soon. I need to apply for opt but I have an employer who can apply for h1b. My questions:

1) can my employer apply for h1b while my opt application is still in process?
2) can my future employer apply for h1b while hiring me? Or I need to be their employee first before they apply for h1b?
3) is there any requirements to the company that wants to apply for me? (I mean number of employees and so on)?

Thanks

You don't need to be the employee first in order to obtain H-1B, and even if you are working for this employer under OPT, they can file H-1B for you if proven the business is qualified and labor certification has been approved, etc. This is a complicated procedures, it's recommended to proceed by experienced immigration attorney.

Thanks for your reply.

Can I work for employer A in one state and apply for H1 with employer B in another state?
What do you mean by "... if proven the business is qualified"?

It's OK if you work under OPT for employer A, but employer B will be the one who file H-1B for you. OPT and H-1B are separate issues. You don't have to work under OPT to be qualified for H-1B but it helps in case you work for the same employer.

".... if proven the business is qualified" means not all US employers can file for foreign workers. That's why the employers have to prove to the labor Department that why the business needs this person...