The experimental procedure and results are described for measurements of the Hall coefficient and electrical conductivity of single crystals and natural specimens of PbS, PbSe and PbTe over the temperature range 77-1000°K. Some measurements at 20°K are also described. The magneto-resistance effect was also measured on some specimens at a number of temperatures between 20°K and 300°K.At high temperatures all specimens show intrinsic behaviour. This will be discussed in detail in a subsequent paper but the behaviour in the extrinsic range, the temperature dependence of the mobility and irreversible effects found at high temperatures are discussed. It is concluded that the general behaviour of the effects considered can be accounted for by the usual semiconductor model.