Rome (FCO) to Venice by train in May

Go to the Trenitalia Website. Enter Fiumicino Aeroporto as the departure station and Venezia S. Lucia as the arrival station. I doubt you will find options for May this far in advance. Pick the same day of the week in January and you should be able to get an idea of the options that are usually available.

Most of the trips are just under five hours, and most of them involve changing trains in Rome, either at Roma Termini or Roma Tiburtina. I’m seeing one direct train at 13:53. It’s possible to get discounts by booking in advance, but it’s not a good idea to do that for your arrival day, in case your flight is delayed and/or it takes an excessive amount of time to clear the formalities at the airport.

The new schedules valid up to June 12 will be uploaded on December 11; January or May makes no difference for now, use a day of travel before December 11. A sunday, if you are travelling on May 1.

Unless you can afford to loose all your money, do not get train tickets for the day of arrival in advance.

Discounted train tickets are cheaper because they can't be refunded: even if you arrive only one minute late at the track, the moment the booked train has left the station those tickets are worthless.

Of course nobody would pay the walk-up "BASE" fare in advance. Anyway note that even these tickets are wasted if you arrive at the track more than one hour after the scheduled departure time of your train.

Book and purchase at the station at FCO after your arrive. Nothing a major delay / cancellation in your flight to make pre-purchased ticket worthless. We have never had a problem getting tickets on a walkup basis at FCO.

Get the Trenitalia app and use that when you arrive

Thank you all so much for the quick reply’s and great information! Grazie!