This letter presents a 300GHz hybrid transceiver using CMOS and InP-HEMT, which achieves a maximum data rate of 56Gb/s. A 300GHz CMOS transceiver with a mixer-last transmitter mixer-first receiver is utilized to up- and down-convert the V-band IF signal to the 300GHz-band, while InP-HEMT is used for PA and LNA design. The transceiver also achieves wireless communication in ch.13-24 (1.76Gbaud), ch.39-44 (3.52Gbaud), ch.52-54 (7.04Gbaud) and ch.59 (10.56Gbaud) with lower than -16.7dB EVM. 64QAM modulation is also achieved for a 5Gbaud symbol rate. The CMOS transmitter and receiver consume 0.29W and 0.17W from a 1V supply, respectively, and the InP-HEMT PA and LNA consume 1.44W from a 1.2V supply.