Lanthanide metaborates Ln(BO2)3 [Ln = La - Tb] form a monoclinic structure with 1d chains of magnetic Ln3+. Their magnetic properties have not been investigated before and they are promising candidates for low dimensional magnetism. Here we focus on Ln = Tb and Pr. Tb(BO2)3 exhibits two sharp long range ordering transitions at 1 K and 1.75 K. We have obtained a magnetic structure for the 1.75 K transition from powder neutron diffraction measurements at D1B, ILL down to 1.5 K. However the reduced moment and presence of strong magnetic diffuse scattering suggests that this corresponds to only partial ordering . Pr(BO2)3 exhibits a broad magnetic ordering transition at 5 K possibly due to short range magnetic correlations.We propose to i) determine the changes in magnetic structure corresponding to the two transitions in Tb(BO2)3 and ii) study the magnetic diffuse scattering in Pr(BO2)3.