We have investigated the adsorption of RuSex (x =1-5) cluster on Se-doped graphene. The change of the adsorption energy with the number of Se atoms and magnetization values are investigated. Electronic properties of adsorption of RuSex (x =1-5) cluster on Se-doped graphene are investigated. The highest adsorption energy belongs to RuSe adsorbate. The biggest magnetization value belongs to RuSe2 adsorbate. This adsorbate makes the substrate half metallic. This property is important in electronic device applications. It is observed that substitutional Se atom changes the electronic properties of graphene. This substitution makes graphene metallic. While RuSe, RuSe4,RuSe5 adsorbate make substrate metallic, RuSe3 makes it semiconducting. Generally, it is found that there is a charge transfer from the substrate to clusters within the Lowdin analysis. This is in line with the charge difference results. (C) 2015 Elsevier B.V. All rights reserved.