Brussels has a very full range of accommodation possibilities, from hostels to five star hotels. The following websites offer a search engine and the possibility of online booking:
BOOKING.COM; VISITBRUSSELS.
Additionally here are some accomodation suggestions as well as how to reach the campus from them...

Brussels Hotel Belgium ****

Avenue Louise 315, 1050 BRUSSELS
Tel: +32(0) 2 640 24 15 - Fax: +32(0) 2 647 34 63
http://www.hotelbrusselsbelgium.com/
reservations@hotelbrusselsbelgium.com

Located right on Boulevard Louise, halfway between the historic centre of Brussels and its green forest, the Bois de la Cambre, the Brussels Hotel offers its guests the ideal location for enjoying the quiet life in Brussels while also being close to the district housing the European Union institutions and the tourist icons in the heart of the city. By either the tramway or the underground, our guests can reach the centre of Brussels in barely five or ten minutes, the home to the most emblematic spots in the Belgian capital: the Grand Place, the Palais Royal, the Palais des Beaux Arts, the Musées Royaux, the Place Royal, the Galeries Royales, the Sablon neighbourhood, the Place De Brouckère, La Bourse, the Theatre de la Monnaie, Manneken Pis and the famous restaurants on Rue des Bouchers.

Route to the campus on Google Maps (approx. 20 min)
To go to the ULB Plaine Campus, walk till the bus stop "Etangs d'Ixelles" and take bus 71 direction: Delta, get off at bus stop "Fraiteur".

Hotel Lambermont ***

Boulevard Lambermont 322, 1030 BRUSSELS (Schaarbeek)
Tel: +32 (0) 2 242 55 95 - Fax: +32 (0) 2 215 36 13
http://www.lambermonthotels.com/
info@lambermonthotels.com

New three star Design Hotel offering rooms, suites, flats, apartments and studios, centrally located between Airport and the City centre of Brussels, approx. 3 KM distance. Very near to the Atomium, the participating building during the world exhibition of 1958. Easy access to the City center and Place de Brouckère with bus 66, to NATO & supermarket Carrefour Evere with bus 65, to European Communities, Heysel, Atomium ,Brupark Village, Kinepolis, Exhibition Center, Baudouin Stadium with the tram 23. Easy transfer from the Airport with the Airport Express Bus 12 (bus stop at Diamant station + tram 23 at 4th stops). At 5 minutes by car from the ring / expressway to all directions.

Route to the campus on Google Maps (approx. 40 min).
To go to the ULB Plaine Campus, walk till the tram stop "Louis Bertrand" and take tram 7 direction: Vanderkindere, get off at tram stop "Etterbeek Station". The ULB Plaine Campus is a ten-minutes walk from that spot.

Hotel Ibis Brussels Centre Ste Catherine ***

Rue Joseph Plateau 2, 1000 BRUSSELS
Tel: +32(0) 2 513 76 20 - Fax: +32(0) 2 514 22 14
http://www.ibishotel.com/ibis/fichehotel/gb/ibi/1454/fiche_hotel.shtml
H1454-RE@ACCOR.COM

The Ibis Brussels Centre Sainte Catherine is located in the centre of Brussels, close to the Grand Place, 5 minutes from the metro and the railway station. The shopping centre and cultural district are a just few minutes walk away. Book one of our 236 modern and comfortable air conditioned rooms and benefit from use of our amenities, 2 meeting rooms, public pay parking, a snack bar open 24 hours and, as business guests will appreciate, WiFi Internet access. Restaurants are available nearby the hotel.

Route to the campus on Google Maps (approx. 25 min)
To go to the ULB Plaine Campus, walk till metro stop "Sainte Catherine" and take metro 5 direction Hermann-Debroux, get off at stop "Delta".