Carbonyl hydrosilylation reaction was developed to prepare reactive blending between PBT and polymethylhydrosiloxane (PMHS). It focused on the addition reaction of Si-H groups from PMHS onto carbonyl groups from PBT catalyzed by triruthenium dodecacarbonyl (Ru-3(CO)(12)). An approach on PBT model compounds was carried out and investigated by NMR spectroscopy to evidence the potentiality and efficiency of carbonyl hydrosilylation reaction. At temperatures up to 100 degrees C, the hydrosilylation reaction can reach 33 mol% conversion in a few hours. Side reactions were also highlighted. Such side reactions can reach more than 23 mol% of the final products when temperature increases to 180 degrees C. Then hydrosilylation reaction was extended to PBT modification with a molar ratio of ester group/SiH=3.5 and viscosity ratio polysiloxane/PBT=4.0 x 10(-5). The reaction was carried out in an internal mixer at 220 degrees C and followed through the evolution of the torque of the reactional medium. Samples for different processing times were investigated by SEM and rheology. From these analyses, the dispersion of PMHS was promoted with diameters of few micrometers. The elastic behavior of final material was characteristic of solid or gel-like structures, suggesting a network structure formation consistent with the gel fraction increase from 0 to 0.55. (c) 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017, 55, 1855-1868