We report the discovery of two new transiting hot Jupiters , KOI-135b and KOI-204b , that were previously identified as planetary candidates by Borucki et al . 2011 , and , independently of the Kepler team , confirm the planetary nature of Kepler-17b , recently announced by Désert et al . 2011 . Radial-velocity measurements , taken with the SOPHIE spectrograph at the Observatoire de Haute-Provence ( France ) , and Kepler photometry ( Q1 and Q2 data ) were used to derive the orbital , stellar and planetary parameters . KOI-135b and KOI-204b orbit their parent stars in \sim 3.02 and 3.25  days , respectively . They have approximately the same radius , R _ { p }  = 1.20 \pm 0.06  \mathrm { R } _ { Jup }  and 1.24 \pm 0.07  \mathrm { R } _ { Jup } , but different masses M _ { p }  = 3.23 \pm 0.19  \mathrm { M } _ { Jup }  and 1.02 \pm 0.07  \mathrm { M } _ { Jup } . As a consequence , their bulk densities differ by a factor of four , \rho _ { p } = 2.33 \pm 0.36 g cm ^ { -3 } ( KOI-135b )  and 0.65 \pm 0.12 g cm ^ { -3 } ( KOI-204b ) , meaning that their interior structures are different . All the three planets orbit metal-rich stars with [ Fe / H ] \sim 0.3  dex . Our SOPHIE spectra of Kepler-17b , used both to measure the radial-velocity variations and determine the atmospheric parameters of the host star , allow us to refine the characterisation of the planetary system . In particular we found the radial-velocity semi-amplitude and the stellar mass to be respectively slightly smaller and larger than Désert et al . These two quantities , however , compensate and lead to a planetary mass fully consistent with Désert et al . : our analysis gives M _ { p }  = 2.47 \pm 0.10  \mathrm { M } _ { Jup }  and R _ { p }  = 1.33 \pm 0.04  \mathrm { R } _ { Jup } . We found evidence for a younger age of this planetary system , t < 1.8  Gyr , which is supported by both evolutionary tracks and gyrochronology . Finally , we confirm the detection of the optical secondary eclipse by Désert et al . and found also the brightness phase variation with the Q1 and Q2 Kepler data . The latter indicates a low redistribution of stellar heat to the night side ( < 16 \% at 1- \sigma ) , if the optical planetary occultation comes entirely from thermal flux . The geometric albedo is A _ { g } < 0.12 ( 1- \sigma ) .