Amorphous thin films of PrxCo1-x alloys were prepared over the composition range 0.06-0.86 by the vacuum evaporation method with two sources. The magnetic properties of those films were measured by using extracting sample magnetometer, vibrating sample magnetometer and the alternating susceptibility set. The dependence of magnetization of these films on temperature and field were studied. It was found that the magnetization has a sudden drop near the temperature corresponding to the maximun of the value of the alternating magnetic susceptibility, and for samples with xco and Pr atom μpr were calculated. The effective magnetic moment of Co atom μco equals l.36f(x), where f(x) is the probability for bearing magnetic moment of cobalt atoms. The effective magnetic moment of Pr atom equals 1.6 μB in. the composition range 0-40% and decreases rapidly in the range 0.4-0.86.