Don't forget to buy food and drinks in advance if you need them: train stations do not always have shops, while onboard cafés are not always available and often very expensive.
For short distances like between Chalcis and Athens, busses and carpooling are good alternatives to the train, thanks to their low costs. Also, busses have the advantage of getting to the smallest towns where the is no train station.
Which stations do the trains to Athens leave from?
You can take the train to Athens at Chalkida, which arrives at Kifissos.
How long will it take you from Chalcis to Athens by train and when do the trains leave?
The first train to Athens leaves at 05:08, whereas the last one at 18:08. On average, the journey lasts 10 hours and 19 minutes, but with the fastest connections you will be in Athens in 2 hours and 37 minutes.