Photo Ionization Mass Spectrometry (PIMS) is a novel sensitive and selective approach in aerosol science for characterization of gases and ambient particulate matter (PM). In this contribution, two PIMS approaches for analysis of aerosols and PM and their applications are presented. On the one hand, an approach where a gas phase PIMS-system is coupled to a Thermal-Optical Carbon Analysis (TOCA, Magee Inc., DRI Model 2015/2) is presented. Carbonaceous material in particulate matter (PM) often is characterized by the organic/elemental carbon content (OC/EC) as measurable by Thermal-Optical Carbon Analysis (TOCA). The coupling of the TOCA EC/OC analyzer to a photo ionization mass spectrometer (PIMS, Photonion GmbH, PhotoTOF) extends the obtainable information to the molecular composition of the different thermal fractions. In particular the profile of the important, highly health-relevant Polycyclic Aromatic Hydrocarbons (PAH) is well detectable by resonance-enhanced multiphoton ionization (REMPI) mass spectrometry (Diab et al.-2015, Miersch et al.-2019a/b). The hyphenated TOCA-PIMS instrument (now commercially available) and selected applications on emission- and ambient-PM characterization are discussed. On the other hand, a novel on-line laser ionization Single Particle Mass Spectrometer (SPMS) approach is depicted. The SPMS System directly analyzes the chemical fingerprint of individual airborne aerosol particles in the diameter range of ~ 10 µm to 50 nm. The development of a new ionization technology was directed to address the most important chemical compound classes for addressing potential health effects (transition/heavy metals, soot, PAH) together with important source markers such as salts, OC, crustal elements (Schade et al 2019, Passig et al. 2022). In addition to an explanation of the SPMS working principle and technical realization also selected applications are presented. This includes the monitoring of emission plumes of ships as well as ambient air studies