Four airports - Dortmund, Münster/Osnabrück, Cologne/Bonn and Düsseldorf - are within a reasonable distance of the Ruhr-University. Düsseldorf Airport, however, is not only the largest, but also the most easily accessed: there are direct connections between the airport and Bochum’s main train station up to eight times per hour, and the journey only takes a good half an hour.
Upon arriving at the airport follow the signs to the DB (Deutsche Bahn) train station. Buy your train ticket to Bochum (Ticket needed: Preisstufe D, €14,60) at the airport before boarding the monorail which takes you to the train station. There are trains travelling directly to Bochum Hauptbahnhof frequently and the trip takes about 35 to 45 minutes depending on which train you take. The ticket Preisstufe D is a ticket provided by the public transportation system VRR and it is only valid in regional trains and S-Bahn. If you take an ICE, IC or EC you need a more expensive ticket for long-distant trains.
Take the shuttle bus from the Airport Terminal to Holzwickede train station. From Holzwickede you take the train to Dortmund Hauptbahnhof (central station) and then change trains to Bochum Hauptbahnhof.
Bochum Hauptbahnhof (central station) is served by ICE, IC, EC, regional and suburban trains at a high frequency. From there, you can reach the University easily by taking underground line U35 straight to the stop Ruhr-University. Take a look at this website for a suitable connection.
The Ibis hotel near central station is a reasonably priced and well located hotel. Also the Kolpinghaus and the Art Hotel Tucholsky can be recommended. For a wider selection of hotels, see Bochum Tourismus hotels