The magnetoresistance of n‐silicon inversion layers is measurd in dependence on the drain voltage at fixed temperatures and vs. tempeature at low drain voltages. A one‐to‐one correspondence of the electric drain fields and temperatures can be deduced from these measurements. The experimental data are taken at temperatures below 30 K. Assuming that the electrons lose energy to acoustic phonos only, the experimental results are compared with a “two‐dimensional hot‐electron” theory. The coupling constant ZA to the acoustic phonons via the deformation potential is found to be ZA = 5.9 eV, which compares favourably with earlier results.