This paper reports low-temperature ac magnetic susceptibility measurements on the Pd x Co 5 0 Al 5 0 - x alloy system with 5 ≤ x ≤ 10. The temperature dependence of the in-phase susceptibility component χ (ω,T) of specimens with x ≤ 8 cooled in a zero magnetic field shows a cusp which is rounded in a magnetic field, indicating rather pure spin-glass behaviour. The positions of the cusps (freezing temperatures, T f ) and the frequencies of the ac field are scaled according to a conventional critical slowing down law. The alloy with x = 10 indicates re-entrant behaviour in the range 18-139 K. The thermoremanent magnetization obeys a logarithmic time dependence.