1,7‐Octadiene (OD) was plasma polymerised onto silicon wafers and glass slides under a broad range of input specific energies and deposition times to study the hydrophobicity of deposited films. Deposition of plasma polymerised 1,7‐octadiene (ppOD) film resulted in decrease of glass slide surface free energy (SFE) from ≈71 to 44 mJ · m⁻². X‐ray photoelectron spectroscopy (XPS) and time of flight secondary ion mass spectroscopy (ToF‐SIMS) results confirmed that this decrease is due to the concealing of polar SiOH groups by non‐polar C_xH_y functionalities. Atomic force microscopy (AFM) images along with ToF‐SIMS spectra suggested patchy‐like growth of ppOD films in the very early stages of polymerisation. It has been demonstrated that a precise control over the surface hydrophobicity is achieved by simply tuning the plasma polymerisation parameters.