The Rutherford backscattering technique with 2 MeV He+ions has been used to measure the range and range straggling of ions implanted into polycrystalline aluminium and amorphous silicon with energies from 20 keV to 250 keV. In aluminium the following ions were used: Cs+, La+, Pr+, Eu+, Tb+, Dy+, Ho+, Er+, Lu+, Hf+, Pt+, Au+, TI+, Pb+, Bi+. In silicon the ions were Sm+, Eu+, Gd+, Tb+and Dy+. The data was converted into reduced range, energy and straggling coordinatesρpε and γΔRp/Řprespectively and graphs plotted against ε In the case of silicon the reduced data fell close to common curves approximated byρp= 1.46 ε0.65and γΔŘp/Řp=0.41 for 0.02 < ε < 0.24. In the case of aluminium the best fit was approximated byρP= 1.95 ε0.60and γΔŘp/Řp= 0.5 for 0.06 < ε < 0.35. The data for Ho+−Al, Au+−Al, Pt+−Si, Au+−Si and Bi+−Si deviated from the common curves over a range of energies. Calculations following the methods of Winterbon using Thomas-Fermi and Lenz-Jensen potentials produced two sets ofppversus ε curves between which all the experimental data lay, with the Thomas-Fermi curves forming a lower limit. Range data from other groups has been collected and reviewed. By combining these with our own the best experimental curves were plotted for the interval 0.0007 < ε < 10.