The present thesis adopts the highly efficient and rapidly developing technique of femtosecond laser mass spectrometry (FLMS) to the analysis of aromatic molecules in the gas and solid phase. Specifically, the above technique couples ultrashort (~80 fs) high intensity (10e14-16 Wcm-2) laser pulses at 800 and 400 nm to a reflectron time-of-flight mass spectrometer. The study is undertaken to characterise the ionisation /dissociation dynamics of a series of aromatic molecules ranging from the protoype aromatic benzene (C6H6), to coronene (C24H12) comprising of 7 fused aromatic rings. In order to extend the powerful, highly efficient ionisation procedure of FLMS to the higher mass solid phase analytes, namely Polycyclic Aromatic Hydrocarbons (PAHs), the technique of laser desorption/femtosecond laser mass spectrometry (LD/FLMS) is utilised, where nanosecond lasers are employed to desorb intact neutral molecules from the solid sample surface, prior to fs post-ionisation. For each of the molecules studied, strong singly and doubly charged parent and satellite ions are observed at both wavelengths, albeit with increased fragmentation under UV irradiation. In addition, strong triply charged parent and satellite ions are observed for the aromatics under IR irradiation and dominant decay channels of the multiply charged ions are identified as loss of Hn and C2Hn. Experimental parameters including wavelength (800 and 400 nm), intensity (10e14-16 Wcm-2), pulse duration (ns and fs), molecular structure and the spatial dependence of single and multiple ion production within a focused laser spot are examined. Ionisation is attributed to a dominant field ionisation regime, particularly under 800 nm excitation, owing to the high intensities employed in the present study.