<p>Dynamic response of fiber-reinforced composites is of increasing basic and applied interest. Plate impact experiments are conducted on polyether ether ketone (PEEK) composites reinforced with carbon fibers (CFs) and glass fibers (GFs). The spallation behavior and interfacial failure mechanisms of CF/GF-reinforced PEEK composites under impact loading are investigated for the first time. Hugoniot equations of state and spall strength, concerning high-pressure shock compression and high-strain-rate tension, are derived from free-surface velocity measurements. Spall strength of the PEEK-CF composite exceeds that of PEEK-GF due to its larger fiber length and stronger interfacial bonding; the fiber-matrix interfaces in the composites give rise to their reduced spall strength compared to pure PEEK. As impact velocity increases, spall strength for both the composites first increases and subsequently decreases due to the competing effects of shock-induced heating and strain-rate hardening. Crack nucleation and propagation depends on interface strength, fiber length and fiber orientation. This study contributes to the understanding of the connections between fiber-matrix interfacial bonding and the dynamic mechanical behavior of fiber-reinforced PEEK composites, and it is helpful for the development and optimization of these materials in protective and structural engineering applications.</p>