The spectral lines $\lambda 226.5,\lambda 441.6,\lambda 806.7$ and $\lambda 853.3$ nm of Cd II and $\lambda 508.6$ nm of Cd I have been studied under high resolution by means of digital recording interferometry. The relative positions of all the stable isotopes of cadmium in all the lines have been deduced from the measurements. The main object of this study was to provide precise data for the simple p-s transitions $\lambda 226.5,\lambda 806.7$ and $\lambda 853.3$ nm. Such lines are the most favourable for theoretical interpretation, and the new results are intended to provide a basis for the separation of mass and field effects in measured isotope shifts in cadmium. The hyperfine structure intervals, which are important in the interpretation of isotope shifts, have also been measured for all the levels involved in the five transitions.