Abstract. The aim of the present investigation was to study the spatio-temporal variability of the microbial activities in coastal saline soils (locally called Khazan) of Goa, India (west coast region). The coastal soil salinity is a major constraint for reduced crop yields and abandonment of farming in these areas. Three replicated global positioning based soil samples (0–0.20 m depth) from each of four salinity groups i.e. non-saline (EC=0.08±0.06 dS m⁻¹), weakly saline (EC=2.04±0.06 dS m⁻¹), moderately saline (EC=3.50±0.57 dS m⁻¹) and strongly saline (EC=5.49±0.49 dS m⁻¹) during three seasons–monsoon, post-monsoon and pre-monsoon were collected. Soil microbial activity in terms of soil microbial carbon (MBC), MBC as a fraction of soil organic carbon (SOC) (MBC/SOC), basal soil respiration (BSR), metabolic quotient (qCO₂) and soil enzyme activities–dehydrogenase, phosphatase and urease was tested. In all the seasons, the soil cationic composition depended significantly (p<0.01) on salinity levels and the exchangeable sodium (Na) was the second most dominant among the tested cations. The MBC, MBC/SOC and BSR reduced significantly with increasing salinity, whereas qCO₂ increased with increased salinity levels. In general, MBC, MBC/SOC and BSR and soil enzyme activities were observed as: salinity levels–strongly saline < moderately saline < weakly saline < non-saline and season–post–monsoon > monsoon > during pre-monsoon season. The mean MBC and MBC/SOC of non-saline soils were 1.61 and 2.28 times higher than that of strongly saline soils, whereas qCO₂ of strongly saline soils was 2.4 times higher than that of non-saline soils. This indirectly indicates the salinity stress on the soil microorganisms. Irrespective of season, the soil enzyme activities decreased significantly (p<0.05) with increasing salinity levels. Suitable countermeasures needs to be taken up to alleviate the depressive salinity effect on the microbial and activity for the sustainable crop production in the coastal saline soils of Goa, India.