We report studies of RT neutron diffraction and low temperature magnetization studies of the Tb_0.9Y_0.1MnO₃ nanoparticles. The neutron diffraction data recorded at room temperature showed the sample to crystallize in an orthorhombic structure conforming to space group Pbnm. From the low temperature magnetization measurements, an antiferromagnetic ordering with a peak in ZFC at T_N = 8K has been observed. There is a splitting in ZFC-FC below ~ 6.6 K. Hysteresis loop recorded at 1.6 K shows a coercive field of ~ 500 Oe and the magnetization does not reach saturation upto 7 T.