Ohio Rev. Code § 3503.011
Qualifications of electors for primary elections
March 23, 1981 House Bill 1062 - 113th General Assembly At a primary election every qualified elector who is or will be on the day of the next general election eighteen or more years of age, and who is a member of or is affiliated with the political party whose primary election ballot he desires to vote, shall be entitled to vote such ballot at the primary election.