Laser resonance ionization mass spectrometry (RIMS) represents one of the most sensitive and selective techniques for ultra trace determination of long-lived radioisotopes. The isotope 99gTc constitutes a specific candidate of high relevance concerning its environmental behavior as well as fundamental research applications. Based on the recent precision determination of the ionization potential of technetium by laser resonance ionization, refined resonant optical excitation pathways have been derived for analytical determination of ultra trace amounts of 99gTc by laser mass spectrometric approaches. The state of the art and the specifications of RIMS-based ultra trace determination for 99gTc, leading to a level of detection of ε ≈ 3 × 10 −4 atoms (3 μBq), are reported.