Early flight, best option to get to Fiumicino from Ostiense?

How early is early? What time is your flight?

If your flight is truly early, you should consider staying at the Hilton that's connected to the airport to save yourself a morning of anxiety. You can walk from there to the departures area of the airport (it's a bit of a walk but still pretty easy). We've done that rather than stress over getting up very early and trying to it to the airport.

How many is 'we'?

Dark and early in the AM, taking a cab would probably be as quick as anything. Taking a cab to catch a bus or train from Termini, does not make a lot of sense to me.

2 adults, 1 teen, 2 under 12. Flight is at 6:30 am. Conventional wisdom around here is at least 2 hours early, maybe 3 for International.

I sent an inquiry to a cab place and we will check out the Hilton and maybe a couple others near by. We had considered spending half a day at Ostia Antica so a room nearby would actually kind of work anyway.

Look at hotels in Fiumicino too - several have shuttles (you'll have to check the times) or can call a cab for you. We've stayed at Hotel Tiber there...

The FL1 train stops at Ostiense on its way to FCO, but it doesn't start running until 05:15, so too late for your flight. I believe the first train from Termini doesn't start early enough for you either.

You might look at the transfer service Rome Cabs.

Taxi or limo service. Your flight departing from FCO is certainly to a European destination therefore 2 hours are more than adequate. A taxi/limo will need to pick you up at 4am.

Great tips all, thank you very much!

We cancelled the final day on our reservation in Ostiense and will look for something closer to the Airport. We had planned to visit Ostia Antica anyway so we will probably shift that around in our schedule so that it is towards the end of our trip and then work the new booking into that idea.

Another vote for the Airport Hilton

Another vote for the FCO airport Hilton, where i stayed in May.