The high-pressure crystal chemistry of coesite was studied by means of single crystal X-ray diffraction in the pressure interval ∼ 2 -34 GPa and at ambient temperature. We compressed the samples using diamond-anvil cells loaded with neon as pressure-transmitting medium and collected X-ray diffraction data using synchrotron radiation. The thermodynamically stable coesite -coesite-I -was observed up to ∼ 20 GPa, with the following unit-cell parameters: a = 6.6533(12) Å , b = 11.9018(10) Å , c = 6.9336(10) Å , β = 121.250(20) ° and V = 469.38(15) Å 3 . The volume-pressure data of coesite-I are described by means of a third-order Birch-Murnhagan EoS with parameters V 0 = 547.26(66) Å 3 ,. Above such pressure we witness the formation of a well crystallized coesite-II, previously observed only by spectroscopic studies. The structure of the novel high-P polymorph was determined and refined at ∼ 28 and ∼ 31 GPa with final R indices of 8% and 12%, respectively. Coesite-II has P 2 1 /n symmetry and a unit cell that is " doubled " along the b -axis with respect to that of the initial coesite-I: a = 6.5591(10) Å , b = 23.2276(14) Å , c = 6.7953(9) Å , β = 121.062(19) ° and V = 886.84(19) Å 3 at ∼ 28 GPa. All Si atoms are in tetrahedral coordination. The displacive phase transition I-> II is likely driven by the extreme shortening (0.05 Å or 3.2%) of the shortest and the most compressible Si1-O1 bond, related to the stiff 180 ° Si1-O1-Si1 angle. Under compression the linear angle bends, resulting in two independent angles, one of which, however, retains almost linear geometry ( ∼ 178 ° ). The requirement of this angle to be close to linear likely causes further Si-O compression down to an extremely short distance of ∼ 1.52 Å which prompts subsequent structural changes, with the formation of a triclinic phase at ∼ 31 GPa, coesite-III.