Rapid kinetic terahertz absorption spectroscopy (KITA) was used to directly probe changes in the collective protein-solvent dynamics during protein folding subsequent to a temperature jump. We monitored changes in the low frequency absorption of the solvated protein lambda(6-85)* with a time resolution of less than 50 mu s. Absorption at low frequency yields information about the collective protein-solvent interaction. The spectral changes below 2 THz are correlated with the hydrophobic collapse of lambda(6-85)*, while there is no indication of any correlation with secondary structure formation, which is an order of magnitude faster. (C) 2016 Elsevier B.V. All rights reserved.