High power density is a desirable feature of power electronics design, which prompts economic incentives for industrial applications. In this paper, a GaN-based 2 kVA singlephase inverter design was developed for the Google Little Box Challenge, which achieves 102 W/in 3 power density. First, the static and dynamic temperature-dependent characteristics of multiple SiC and enhancement-mode GaN FETs are investigated and compared. Based on the device testing results, several topologies of the inverter stage and different power decoupling solutions are compared with respect to device volume, efficiency, and thermal requirements. Moreover, some design approaches for magnetic devices and the implementation of gate drives for GaN devices are discussed in this paper, which enable a compact and robust system. Finally, a dc notch filter and a hard switching full bridge converter are combined as the proposed design for the prototype. A 2 kVA prototype is demonstrated which meets the volume, efficiency and thermal requirements. Performance of the prototype is verified by experimental results.