The 141 P was designed shortly after the founding of the SNCF as a powerful, fast mixed-traffic locomotive that was desperately needed. It was based on the PLM Mikados No. 1 to 680, but had been considerably reworked by André Chapelon. A total of 318 were ordered from several manufacturers. Production was often delayed after the German invasion since the companies now had to build German standard locomotives like the class 44. So the last one was only delivered in 1952.

Like its basis, it was a four-cylinder compound where the cylinders were placed against typical French practice, with the high pressure cylinders on the outside and the low pressure cylinders on the inside. Both sets of cylinders were controlled by a single reverser and the start valve was operated by a separate lever. The leading axle was connected to the first driving axle by a Bissel bogie that allowed for some lateral movement of the driving axle. 

With internal streamlining, a double Kylchap exhaust and a stoker, they delivered an indicated output of 3,900 hp. This was enough for express trains of 550 tonnes and freight trains of 1,200 tonnes. Although they easily ran up to 125 km/h, approval was only granted for 105 km/h. When the American 141 R was introduced, it was found out that the French locomotives were more expensive to build and maintain, but consumed 30 percent less. Nevertheless, the 141 P was partly replaced by the 141 R and partly by electrification. The last one was withdrawn in 1969 in the Est region.