Pulsed neutrons generated in a plasma focus device are used for the thermal neutron activation analysis (TNAA) of selected three elements having widely different half-lives varying from a few seconds to a few days [Dysprosium (Dy), Manganese (Mn) and Gold (Au)]. Neutron pulse having strength of (1.2 ±0.3) ×10⁹ neutrons/pulse with a pulse width of 46 ±5 ns is produced by “MEPF-12” device operated at a filling gas (deuterium +0.5% krypton) pressure of 3 mbar. The fast 2.45 MeV D–D neutrons are thermalized before irradiating the sample. The decay gammas from the radioisotopes ^165mDy (T_1/2=1.26min.), 56Mn (T_1/2=2.58hrs.), and ¹⁹⁸Au (T_1/2=2.69 days) produced via reactions, ¹⁶⁴Dy(n, γ)^165mDy, ⁵⁵Mn(n, γ) ⁵⁶Mn, and ¹⁹⁷Au(n, γ) ¹⁹⁸Au respectively are counted off-line in a lead shielded well type 76 ×76mm² NaI(Tl) detector coupled to a calibrated 2048 channel analyzer. The values of half-lives evaluated from the measured decay gammas, 1.43 ±0.3 min., 2.56 ±0.5 hrs. and 2.84 ±0.6 days respectively for the radioisotopes of Dy, Mn and Au, are seen to be close to the values reported in literature.