SrEr_2O_4 has been characterised by low-temperature powder neutron diffraction, as well as single crystal specific heat and magnetisation measurements. Magnetisation measurements show that the magnetic system is highly anisotropic at temperature above ordering. A magnetic field of 280 kOe applied at T=1.6 K does not overcome the anisotropic magnetisation and fails to fully saturate the system. Long range antiferromagnetic ordering develops below T_N=0.75 K, identified by magnetic Bragg

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... ns with propagation vector k=0 and a lambda anomaly in the specific heat. The magnetic structure consists of ferromagnetic chains running along the c axis, two adjacent chains being stacked antiferromagnetically. The moments point along the c direction, but only one of the two crystallographically in-equivalent Er sites has a sizeable ordered magnetic moment, 4.5 μ_B at 0.55 K. The magnetic properties of SrEr_2O_4 are discussed in terms of the interplay between the low-dimensionality, competing exchange interactions, dipolar interactions and low lying crystal field levels.