The electrical resistivity (p) and the absolute thermopower (S) of high-purity Yb₂Cu₉ have been measured between 1.2 and 300 K at pressures up to 17 kbar and in magnetic fields up to 6 T. At zero pressure the three measured samples show a Kondo peak in the resistivity at 17 K. Furthermore for one of them the resistivity rises below 5 K. Under pressure, the Kondo peak in p slowly moves towards lower temperatures indicating a decrease of the Kondo temperature TK, in good agreement with specific heat results. The increase of p below 5 K disappears completely for pressure lower than 1 kbar and the residual resistivity remains high. The thermopower S exhibits similar trends. Magnetic field dependences of both p and S are weak. No evidence of magnetic ordering has been detected up to 17.6 kbar.