Due to the special characteristics of Tencel fibres, it is important to gather new data and information in order to improve our knowledge of their performance during dyeing. Kinetic equations are used to describe the behaviour of the heterogeneous dye-fibre system under isothermal conditions in order to determine the evolution of dye exhaustion versus dyeing time. Direct dyes are particularly suitable because they are physically absorbed and because they exhibit outstanding substantivity to cellulose. In addition, some of these dyes have a linear structure which ensures good correlation with structural differences in the fibres. The aim of this study is to quantify the kinetic behaviour of the Tencel-C.I. Direct Blue 1 system (one of the most common dyes in dyeing studies) by using three bi-parametric empirical dyeing-rate equations and a continuous-flow dyeing cell to obtain experimental data at six different temperatures: 30, 40, 50, 60, 70 and 80ºC. In order to check the level of adjustment of the equations we record the at three exhaustion levels: 50%, 80%, and final exhaustion