The high-pressure behavior of fully intercalated lithium cobaltite, LiCoO2, has been investigated by angle-dispersive synchrotron x-ray powder diffraction and Raman spectroscopy. The layered structure (Rm) is found to exist up to at least 26 GPa. From refinements of x-ray diffraction patterns information is derived on changes of Co-O and Li-O bond lengths under pressure. The stability of the ambient-pressure phase is confirmed by Raman spectroscopy. The pressure coefficients for the A1g and Eg Raman modes and their mode-Grüneisen parameters are reported as well as qualitative observations concerning unusual changes in width and intensity of the Raman lines under pressure. The obtained high-pressure structural and vibrational properties are compared to results of ab initio calculations.