Abstract: Electrospray-assisted laser desorption ionization (ELDI) and laser-induced acoustic desorption (LIAD) mass spectrometry (MS) are useful techniques for directly characterizing small chemical or large biological components in solid or liquid under ambient conditions. Sample pretreatment is usually unnecessary for both techniques. The analytes molecules in the samples are desorbed by the action of a pulsed laser without the assistance of organic matrix. The desorbed molecules are subsequently ionized in an electrospray plume generated by electrospraying an acidic methanol solution. Recently, we have modified the existing ELDI and LIAD sources so unique applications are performed: 1) High throughput TLC/MS analysis - the TLC plate was linearly scanned by the laser from either side of the plate. Typically the systems allow to continuously screening up to 400 TLC plates per day. 2) Molecular imaging analysis - with the assistance of a stepper motor for precisely moving the sample plate and a high spatial resolution laser, the distribution of the predominant chemical compounds on a particular sample surface were obtained. The molecular images based on volatile and non-volatile chemical compounds on dry fungus and plant slices were obtained. 3) Monitoring chemical reaction - the states of ongoing chemical reactions－nanoparticle catalyzed photodecomposition of dye molecules in different organic solvents, were continuously monitored. 4) Protein structure study - the change of protein structure was studied via H/D and D/H exchange. The amino acids, peptides, and proteins with different exchangeable H atoms were chosen to ascertain the number of H/D or D/H exchanges in a reactive-ELDI/MS system. In addition, a new configuration of the electrospray system was built for both ELDI and LIAD sources. A multiple electrosprayer system was used to generate an atmosphere containing homogenously charged species. The efficiency of post ionization of the desorbed analyte molecules in the new ion sources is greatly increased. Different solvent systems can be simultaneously used to produce electrospray plumes to ionize the analyte molecules with different polarities.