This study was carried out to determine the effects of three types of humic acids (HA1 and HA2 and HA3) and different humic acid concentrations (0, 250 and 500 mg L-1) on seed germination of ten halophytic species under two thermoperiods (10/20 and 20/30 oC); two photoperiods (12/12h dark/light and 24h dark) and two NaCl treatments (nonsaline control vs. salinity reported to induce 50% germination inhibition, respectively). Humic acid did not seem to alleviate seed germination of most halophytes under nonsaline conditions at sub-optimal thermoperiod (10/20 oC) except for Aeluropus lagopoides andArthrocnemum macrostachyum. Humic acid alleviated seed germination of Urochondra setulosa in the presence of light (12/12h; light/dark photoperiod) under saline conditions. Lower concentration (250 mg L-1) of the three humic acid types improved seed germination of Aeluropus lagopoides, Cyperus conglomeratus, Desmostachya bipinnata, Halopeslis. perfoliata, Pharagmites karka under saline conditions in the absence of light. However, all humic acids at 500 mg L-1 alleviated the salinity effects on seed germination of Sporobolus ioclados. Humic acid treatments could partly substitute the light requirement of few halophyte seeds germinated under saline conditions. The role of humic acid (HA1) was also studied on the seedling growth, water relations, ion regulation and photochemistry of Urochondra setulosa under saline conditions (0, 300 and 600 mM NaCl). Plants maintained water use efficiency regardless of increasing NaCl concentrations but the increase in Na+ was counter-balanced by lowering Na+/K+ ratios of root and shoot. Selective absorption of K+ over Na+ was improved by humic acid in both NaCl treatments where as, K+ over Na+ transport was improved only in 600 mM NaCl. Humic acid improved electron transport rate (rETR) and Non-photochemical quenching of fluorescence (NPQ) at 600 mM NaCl. Humic acid treatment improved anti-oxidant defense at cellular level by decreasing the percentage of blue stained cells, malondialdehyde (MDA),and hydrogen peroxide(H2O2) in leaves under saline conditions. Humic acid application appears to be a low cost bio-stimulant for enhancing seed germination and growth of halophytes under saline conditions.