Calcium phosphate-based (CaP) coatings on metallic implants and particularly, hydroxyapatite Ca10(PO4)6(OH)2 (HAP), stand as leading biomaterials because of the remarkable osseoconductive properties. Among the existing coating techniques, electrostatic spray deposition (ESD) based on electrohydrodynamics offers a versatile bottom-up approach to develop robust coatings in one step and simultaneously tune their key properties: i) texture (ranging from dense coatings to sophisticated hierarchical porous architectures) using SEM, ii) structure and crystallinity (ranging from simple amorphous materials to multi-phase nano-micro crystalline compounds) using X-ray diffraction, FTIR and Raman spectroscopies, and iii) chemical composition using EDS and ICP-AES. The precise control over these three key properties lies in the interplay of the employed ESD protocol and the overall composition of the deposition solution. This work aims to understand the behavior of the P(V) precursor in the ESD process and to achieve the deposition of single-phase HAP coatings. Single-phase and nanostructured HAP coatings crystallizing in a hexagonal symmetry are successfully obtained by using triethyl phosphate (TEP) as a P(V) precursor and calcium nitrate as a Ca(II) precursor. Due to the alkoxide nature of TEP, the effective incorporation of P(V) in the coatings is conditioned by the competition between hydrolysis/evaporation of TEP during the deposition.