This paper deals with the results of experiments on the viability and culture of the microalga, Nannochloropsis oculata under preserved conditions. Uncentrifuged samples were kept in refrigerator (without cryoprotector) to observe the duration of viability and the algae could be maintained for 18 months by cooling. The cell quality under cooled culture condition was observed to be better and indicated the population growth similar to regular continuous culture after reinoculation. Variation in growth rate and cell concentration were observed between Walne's and Locally Developed Nutrient Medium (LDM). The cooling method preservation was most simple and effective for N.Oculata. Twelve months old preserved samples of cooled culture were raised and inoculated to outdoor mass culture using LDM.