Specification is one form of accession of movables. Specification exists when a person by his work and another's material creates a new thing, provided there is no contractual relationship between the person doing the work and the owner of the material used. In such case, the question arises who has the property rights to the new thing. As we can observe, the specification is not completely regulated in the Serbian legislation. In this paper, the concept of specification is determined taking into account the opinion of various authors. Some practical examples and implications are given regarding the change in the ownership regime of specified things in terms of the existing regulation, bearing in mind the historical background, as well as newly proposed Serbian legislation.