Constitution of the State of Ohio Art. II, § 8

Each general assembly shall convene in first regular session on the first Monday of January in the odd-numbered year, or on the succeeding day if the first Monday of January is a legal holiday, and in second regular session on the same date of the following year. Either the governor, or the presiding officers of the general assembly chosen by the members thereof, acting jointly, may convene the general assembly in special session by a proclamation which may limit the purpose of the session. If the presiding officer of the Senate is not chosen by the members thereof, the President pro tempore of the Senate may act with the speaker of the House of Representatives in the calling of a special session.