| Riolos | |
| Name Local: | Ρίολος |
| Type: | community |
| Periph: | West Greece |
| Periphunit: | Achaea |
| Municipality: | West Achaea |
| Pop Community: | 494 |
| Population As Of: | 2021 |
| Elevation: | 100 |
| Coordinates: | 38.0167°N 49°W |
| Postal Code: | 270 52 |
| Area Code: | 26930 |
Riolos (Greek, Modern (1453-);: Ρίολος) is a village and a community in the municipal unit of Larissos, Achaea, Greece. It is located on the northwestern edge of the Movri hills, 4 km north of Mataragka, 3 km southwest of Krinos, 6 km southeast of Lappas and 32 km southwest of Patras. The community includes the small village Mazaiika. The river Larissos flows southwest of the village. During the Greek War of Independence a battle took place in Riolos in which the Greeks, led by Thallis Theodoridis the Elder, were victorious.
| Year | Population | |
|---|---|---|
| 1981 | 757 | |
| 1991 | 708 | |
| 2001 | 801 | |
| 2011 | 545 | |
| 2021 | 494 |