Co and Nd co-substituted Bi5Ti3FeO15 thin films were prepared on Pt/Ti/SiO2/Si substrates via metal organic decomposition method. The structural and multiferroic properties of the films were investigated. It was found that Co ions enter into the lattice and occupy the Fe site. The Bi4.15Nd0.85Ti3Fe0.5Co0.5O15 films simultaneously exhibit ferroelectric and ferromagnetic properties at room temperature, and its 2P(r) and 2M(r) are 38 mu C/cm(2) and 3 kA/m, respectively. Moreover, substitutions create local ferromagnetic order and antiferromagnetic order depending on whether the local bonding is Fe-O-Co or Fe-O-Fe/Co-O-Co, respectively. The competing interaction of the ferromagnetic and antiferromagnetic phases results in an interesting magnetic behavior of the films. (C) 2012 Elsevier B.V. All rights reserved.