Trains leave Frankfurt's Hauptbahnhof for Gelnhausen every 30 minutes during the day. Most of these trains are direct, but some require a transfer at Hanau.
From Hanau , follow the autobahn (A66) into Gelnhausen.
Note: This information was accurate when it was published, but can change without notice. Please be sure to confirm all rates and details directly with the companies in question before planning your trip.