The ‘‘hyperfine magnetic field’’‐Hhpfat the nuclei of the diamagnetic atoms119Sn was measured in Heusler alloy Ni2MnSn by Mo¨ssbauer absorption spectroscopy for pressures up to 10.8 GPa at room temperature. The pressure dependences ofHhpfSndoes not show hysteresis and can be fitted by a linear functionHhpfSn(P)/HhpfSn(0) =1+kH⋅Pwith the coefficientkH=−0.095±0.015 GPa−1, whereHhpfSn(0)=4.60±0.12T. Diamond anvil cells were used to obtain high pressure at room temperature. The Curie temperature (TC) has been measured (up to 5.2 GPa) in the ‘‘toroid’’ high pressure device using thermal ac susceptibility measurements. That pressure dependence was linear with the coefficientdTC/dP=7.44 K/Gpa [TC(0)=341.3 K]. The compressibility of the sample has been measured by means of resistive strain gauges at hydrostatic pressure up to 9 GPa. The equation (V−V0)/V0=−a⋅P+b⋅P2has been fitted to the experimental data with the coefficientsa=8.64⋅10−3GPa−1,b=1.13⋅10−4GPa−2. The drop of theHhpfSnin pressure range 0–10.8 GPa can be explained on the basis of the empirical theory developed by Delyagin, Krylov, and Nesterov [JETP76, 1049(1980)]. ©1996 American Institute of Physics.