The dataset compiles morphological measurements of coccoliths (Gephyrocapsa spp.) from one sample from the Western Equatorial Pacific. The morphological measurements were applied to evaluate coccolithophore preservation aspects under different dissolution intensities in a laboratory experiment. For the dissolution experiment, we added different amounts of Calgon solution (0, 0.4, 0.8, 2, 4, and 6 ml) in subsamples prepared from one sediment sample (ODP 807A-2H2W57-59 cm). The length, volume, area, and mass were obtained using the C-Calcita software from images taken under a cross-polarized microscope (Zeiss AX10). Thickness and the shape factor ks were calculated. The columns include the sample name, how much Calgon was added into sediment suspension, the number of coccoliths measured per sample, length, mean ks shape factor and standard deviation of mean ks/mean ks.