Oulun Suomalaisen Yhteiskoulun Lukio (abbr. OSYK, English: Finnish Co-educational Lycée of Oulu) is a Finnish-language upper secondary school in Oulu, Finland. The school is located in the Kuusiluoto neighbourhood in the Vanhatulli district in the central Oulu.

There are about 40 teachers and about 620 students in OSYK. The school is arts and culture oriented, and it is part of the UNESCO Associated Schools Network.