This document focuses on the study of viscoelastic and mechano-sorptive behaviour of the following tropical species: Aucoumea klaineana Pierre (okume), and Pterocarpus soyauxii Taub (padouk). The specimens were tested in 3-point bending under mechanical load and constant temperature at different relative humidity cycling from 40 to 75% for 14 days. The specimens were tested at a low stress of 10% of the ultimate tensile strength. Control specimens of the species were also placed in the box for moisture content monitoring by mass weighing. The deflection is measured by linear LVDT transducers. The results of this work show how the strains increase as a viscoelastic effect and how the strain id increased by the mechano-sorptive effect. It has also been observed that the humidification phases cause a decrease of the strain except during the first humidification, unlike the drying phases which increase the strain.