The complex [RhCp*Cl(mu-Cl)](2) (Cp* = C5Me5) reacts with RNH2 (R = C6H5, p-CH3C6H4, p-CH3OC6H4, p-ClC6H4 and p-BrC6H4) in dichloromethane to form the corresponding pentamethylcyclopentadienylrhodium(III) derivatives [RhCp*Cl-2(RNH2)]. The compounds have been characterized by C, H and N analyses and spectroscopic methods (IR and H-1 NMR). The TG, DTG and DSC study of the complexes was carried out in both dynamic nitrogen and air atmospheres. From the DSC curves the heat of decomposition was calculated. The kinetics of the first step of thermal decomposition were evaluated from TG data by means of Coats-Redfern, MacCallum-Tanner and Horowitz methods and the procedure proposed by Dollimore et al. The values of the activation energy, E-a, and the pre-exponential factor, A, of the thermal decompositions were calculated.