Tomasz Wąsowicz's research was first related to high-resolution atomic spectroscopy and focused on measurements and analysis of the transition probabilities of the forbidden lines, the hyperfine and isotopic structure of spectral lines of heavy elements, Stark effect in the helium atom. Tomasz Wąsowicz currently studies physicochemical processes occurring during interactions of various forms of radiation with atoms and molecules in a gas phase. In particular, his work concerns collisions of structural units of biologically active molecules or their analogs with charged particles (e^–, H_n=1-3⁺, He^+/2+, C⁺, O⁺), as well as measurements of synchrotron radiation-induced mechanisms of photoexcitation, photoionization, and photodissociation of molecules using photon induced fluorescence spectroscopy (PIFS), NEXAFS absorption spectroscopy, and mass spectrometry. In addition, to explore and elucidate the nature of the structure of high Rydberg levels, post-collisional effects, and core-edge dynamics of biological molecules and molecules of environmental interest, T. Wąsowicz implemented or developed several innovative techniques of high-resolution collision spectroscopy, including photon-photon coincidences (PPCO), photoelectron-positive ion coincidences (PEPICO), negative ion-positive ion coincidences (NIPICO) and mass spectrometry with time-of-flight (TOF) analyzer and pulsed electric field ionization (FIS). T. Wąsowicz's publication record includes 63 scientific articles, 42 of them in renowned journals indexed in JCR, 12 popular ones, editions of three books, and 62 presentations at international and national conferences. He has participated in 11 research projects - eight foreign, in which he led international teams four times, and three domestic, in which he was a leader once. He has received awards, honors, and scholarships for his scientific and organizational work.

Privately, T. Wąsowicz is passionate about karate, swimming, business psychology, and motivation.  He won the Polish university powerlifting championship and the silver medal at the Polish Shorin-ryu karate championship.