(\mathrm{LiNiO}{2}) is a member of the solid solution series (\mathrm{Li}{4} \mathrm{Ni}{2-x} \mathrm{O}{2}) and has been suggested as an experimental spin (\frac{1}{2}) triangular lattice antiferromagnet. It is therefore thought to be a good candidate for spin liquid behavior. We have carried out detailed structural studies using powder X-ray and neutron diffraction with Rietveld profile refinement on five different samples of (\mathrm{Li}{x} \mathrm{Ni}{2-x} \mathrm{O}{2}) with (x) near 1 . The results show that there are always some nickel atoms occupying sites in the lithium layers even when (x=) 1. We show that the presence of nickel atoms in these sites profoundly affects the magnetic behavior and can easily explain the differences in magnetic behavior for (\mathrm{LiNiO}{2}) previously reported in the litcrature. Magnetic susceptibility data on these samples show high temperature behavior similar to previously reported results. At low temperatures spin glass freezing is observed at (T_{\mathrm{f}}=9 \mathrm{~K}) for samples with (x=1). Low-field measurements on such samples are necessary in order to see this cleatly. A simple exchange model is proposed which explains most of the experimental results, thus showing that the spin liguid interpretation of previous workers is unnecessary. เค 1993 Academic Press, Ine.