German Railways (DB) operates a train from Berlin to Köthen hourly. Tickets cost $30 - $50 and the journey takes 1 h 44 min. German Railways (DB) also services this route hourly. Alternatively, BVG operates a bus from Berlin to Köthen every 10 minutes. Tickets cost $3 - $5 and the journey takes 26 min. 2 other operators also service this route.
From Berlin Alexanderplatz train to Dessau Hbf then train to Köthen. 2 h 30 min 37€. From S+U Alexanderplatz line 100 bus to S+U Zoologischer Garten Bhf, bus to Berlin, Berlin central bus station, then bus to Köthen. 3 h 41 min 16€. From Berlin drive to Köthen. 1 h 42 min 20€.