The dynamic characteristics of the catenary-pantograph interface in high-speed trains are evaluated. During a test run signals from accelerometers, load cells, and strain gauges attached to various parts of the pantograph assembly are collected and processed. The signals are analyzed in both the time and frequency domains to determine the dynamic characteristics of the catenary-pantograph interface constituting the critical part of the current collection system of the high-speed train. It is found that there are major frequency components of the pantograph motion at the interface that shift in direct proportion to the train speed as well as components that are stationary in the frequency domain such as the 8.5 Hz component representing the fundamental resonant mode of the panhead assembly. The contact force at the interface shows that while the mean contact force stays almost invariant, the fluctuating component is significantly dependent on the filtering frequency applied to the accelerometer signal during estimation of the inertia force of the panhead. An important implication of the finding is that analytical or numerical investigations based on lumped element models of the pantograph may provide accurate predictions on mean values of the contact force at the catenarypantograph interface, but are inherently limited in estimating high-frequency fluctuations in the contact force. Since the ratio of the fluctuating portion to the steady-state portion (i.e., the mean value) increases with increased train speed, the predictive capacity of the investigations based on numerical simulations diminishes with increasing train speed.