Pulsed plasma polymerization of benzaldehyde is used to produce thin films containing aldehyde functional groups. The effects of pulse peak power, pulse-on time, duty cycle, and monomer pressure on film composition, especially aldehyde functional groups, and surface polarity are examined. Film properties are determined using Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), contact angle measurements, and scanning electron microscopy (SEM). Analysis using these techniques shows retention of the aromatic structure occurs with the longest off times and smallest duty cycles while retention of the aldehyde group occurs only under plasma conditions that result in fragmentation of the aromatic ring, higher peak pulse power, and a relatively large duty cycle (20%).