CePt2In7, a new antiferromagnetic heavy fermion compound, is a member of CeMxIn3+2x family (among them CeIn3 and CeCoIn5). It demonstrates novel and unusual physical properties, such as a pressure-induced quantum critical point and unconventional superconductivity.Previous NQR studies performed on single crystals suggest a coexistence of an incommensurate and commensurate antiferromagnetic components, whereas only commensurate phase was observed in polycrystalline samples. So far, no neutron diffraction experiments on CePt2In7 have been reported. Such measurements are crucial for resolving this apparent controversy.A rapid one-day test on the D23 diffractometer on our very high quality sample suggests the existence of a commensurate propagation vector at 1.5 K. Built on these preliminary results, we propose to determine the details of the magnetic structure by single crystal neutron diffraction. To this end, the measurements will be performed over a temperature range from 1.5 K to above TN = 5.5 K in order to check carefully the existence of an incommensurate antiferromagnetic order and determine the value and orientation of the magnetic moments and their temperature dependence.