Context :

Aims : The SHINE program is a high-contrast near-infrared survey of 600 young , nearby stars aimed at searching for and characterizing new planetary systems using VLT/SPHERE ’ s unprecedented high-contrast and high-angular-resolution imaging capabilities .
It is also intended to place statistical constraints on the rate , mass and orbital distributions of the giant planet population at large orbits as a function of the stellar host mass and age to test planet-formation theories .

Methods : We used the IRDIS dual-band imager and the IFS integral field spectrograph of SPHERE to acquire high-contrast coronagraphic differential near-infrared images and spectra of the young A2 star HIP 65426 .
It is a member of the \sim 17 Myr old Lower Centaurus-Crux association .

Results : At a separation of 830 mas ( 92 au projected ) from the star , we detect a faint red companion .
Multi-epoch observations confirm that it shares common proper motion with HIP 65426 .
Spectro-photometric measurements extracted with IFS and IRDIS between 0.95 and 2.2 \mu m indicate a warm , dusty atmosphere characteristic of young low-surface-gravity L5-L7 dwarfs .
Hot-start evolutionary models predict a luminosity consistent with a 6 - 12 M _ { Jup } , T _ { eff } = 1300 - 1600 K and R = 1.5 \pm 0.1 R _ { Jup } giant planet .
Finally , the comparison with Exo-REM and PHOENIX BT-Settl synthetic atmosphere models gives consistent effective temperatures but with slightly higher surface gravity solutions of log ( g ) = 4.0 - 5.0 with smaller radii ( 1.0 - 1.3 R _ { Jup } ) .

Conclusions : Given its physical and spectral properties , HIP 65426 b occupies a rather unique placement in terms of age , mass , and spectral-type among the currently known imaged planets .
It represents a particularly interesting case to study the presence of clouds as a function of particle size , composition , and location in the atmosphere , to search for signatures of non-equilibrium chemistry , and finally to test the theory of planet formation and evolution .