Chalkida is 70km away from Athens. The easiest way to visit Chalkida is by car. Drive north at national road Athens-Lamia and at the 60th km turn right. Chalkida is 15km away from there.
There are also several buses every day (70’ ride, the first one at 05:30) from Athens and also buses from many towns of Evia(Edipsos, Aliveri, Karistos etc) and other big cities of Greece like Thesaloniki(5 hours ride, 2 buses per day, 26euro ticket), Ioannina(1 bus every day) etc
In the past I used to visit Chalkida by train(85’ ride). The first train from Athens is at 04:10 and the last at 22:50. The first train from Chalkida is at 04:45 and the last one at 23:10. The train ticket costs about 4 euro.
The train station of Chalkida (2’ walk from the old bridge) is a beautiful like many of the stations along the greek railway. 20’ away from Chalkida, at Inoi train station you can catch the train for other greek cities like Larisa, Thesaloniki etc
There is two main ways to go to Chalkis. First, you can go there by bus. There are busses from Athens every 30 min from 06.00 to 21.00 costing about 5 euros, and the trip lasts 1.15h. Furthermore there are busses form Thessaloniki twice per day at 09.00 and 16.00 and the trip lasts about 5h. Second way to go to Chalkis is by train. There are trains every about 1h from Athens from 05.00 till 23.00, costing 4,5 euros and the trip lasts 1.30h. Those trains are direct from Athens to Chalkis. There is a train station 30 min away from Chalkis where you can change train and travel all over the Greece, this train station is called Oinoi. You can pick up your ticket from Chalkis train station and take a look to the schedule.
You can hardly see the train behind the trees, it is the end of the train station. Or would you prefer a boat?