Abstract: Terahertz (THz) communications are expected to be the next frontier for wireless nanonetworks. Nanonetworks are formed by nanodevices (tiny devices at the nanoscale or molecular scale). The high transmittable data rate for nanonetwork is investigated based on a new model of the THz wave atmospheric propagation of attenuation. The THz wave atmospheric attenuation experimental results obtained from the THz-time domain spectroscopy (THz-TDS) technique are analyzed using this model. The intensity and location of the observed absorption lines are in good agreement with the calculated spectrum. The total path loss and the maximum transmittable data rate are numerically simulated when a THz wave propagates over an extremely short distance. Furthermore, the channel capacity in the THz band (0.1-5 THz) is investigated by this mode. It is shown that the molecular absorption loss is significant in THz band; data with high rates of more than 100 Gbit/s, which take advantage of the unique characteristics in the physical channels while minimizing the impairments of molecular absorption, can be transmitted via the THz channels for a greatly short transmission distance.