It is an object to provide a liquid composition for forming a thin film, with which a ferroelectric thin film having excellent characteristics can be prepared even by baking at a low temperature, and a process for producing a ferroelectric thin film using it. The above object is achieved by use of a liquid composition for forming a ferroelectric thin film, characterized in that in a liquid medium, ferroelectric oxide particles being plate or needle crystals, which are represented by the formula ABO3 (wherein A is at least one member selected from the group consisting of Ba.sup.2+, Sr.sup.2+, Ca.sup.2+, Pb.sup.2+, La.sup.3+, K.sup.+ and Na.sup.+, and B is at least one member selected from the group consisting of Ti.sup.4+, Zr.sup.4+, Nb.sup.5+, Ta.sup.5+ and Fe.sup.3+) and have a Perovskite structure and which have an average primary particle size of at most 100 nm and an aspect ratio of at least 2, are dispersed, and a soluble metal compound which forms a ferroelectric oxide by heating, is dissolved.