An angular analysis of the decay $$ {B}_s^0\to {K}^{\ast 0}{\overline{K}}^{\ast 0} $$ is performed using pp collisions corresponding to an integrated luminosity of 1.0 fb−1 collected by the LHCb experiment at a centre-of-mass energy $$ \sqrt{s}=7 $$ TeV. A combined angular and mass analysis separates six helicity amplitudes and allows the measurement of the longitudinal polarisation fraction f L = 0.201 ± 0.057 (stat.) ± 0.040 (syst.) for the $$ {B}_s^0\to {K}^{\ast }{(892)}^0{\overline{K}}^{\ast }{(892)}^0 $$ decay. A large scalar contribution from the K 0 ∗ (1430) and K 0 ∗ (800) resonances is found, allowing the determination of additional CP asymmetries. Triple product and direct CP asymmetries are determined to be compatible with the Standard Model expectations. The branching fraction $$ \mathrm{\mathcal{B}}\left({B}_s\to {K}^{\ast }{(892)}^0{\overline{K}}^{\ast }{(892)}^0\right) $$ is measured to be (10.8 ± 2.1 (stat.) ± 1.4 (syst.) ± 0.6 (f d /f s )) × 10−6.