This dataset contains data obtained from experimental work of the effect of hydroxylpropyl methylcellulose (HPMC) type (with low and high content of methyl and hydroxypropyl groups: HPMC-L and HPMC-H) and concentration (4, 6, 8 and 10% w/w of HPMC-L and 2, 3, 4 and 5% w/w of HPMC-H) on the formation, stability, and microstructure of conventional emulsions and nanoemulsions made with extra virgin olive oil, and stabilised with lecithin and HPMC. The data was obtained using a high-speed homogenizer and a high-pressure homogenizer to form the emulsions; a dynamic light scattering (DLS) instrument (mean droplet diameter, polydispersity index and ζ-potential), a spectrophotometer (TBARS), a Chroma Meter (colour), a rheometer (viscoelasticity and thermogelation), a pendant drop analyser (surface tension), and a texture analyser (firmness and spreadability).