Nikolaiika (Greek: Νικολαίϊκα) is a village in the municipal unit of Diakopto, Achaea, Greece.

The Greek National Road 8A (Patras - Aigio - Corinth) passes south of the village.

The Geometric period temple (8th century BC) has been excavated in its eastern half, where the entrance, including an apsidal porch, is located; the western half is still unexcavated.

Small-sized votive offerings of chariot wheels have been found, suggesting that this was a temple dedicated to Poseidon, the god who, according to the belief of the time, caused earthquakes by riding in his chariot.

The excavation is being led by Greek archaeologists Erofili Kolia and Anastasia Gadolu.