Abstract: Cell type studied in this work is human leukemic cell Jurkat. In order to identify the exponential growth phase, the better time for sampling the population, the cell line was evaluated by monitoring the proliferation and viability of the cells in a 7-days long culture adding no medium to the cells. It was found that the culture within the cellular concentration from 6x105-2.7x106 cells/ml was in the exponential or log phase, where the viability and reproduction for the cells were high. The lag time and population doubling time were calculated and found to be 1 and 5 days respectively. The density dependent survival of cells in culture was remained constant, with the exception at very higher cell densities where it was found to decrease slightly. The viability of the cells was found to remain within 96-97% at incubation temperature range 10-500C, with a maximum at 35-400C. The cells were then incubated with 1 mM ALA at different temperatures and irradiated with different light doses. The dose-response curves were studied and modeled. The cell survival for incubation temperatures 10-370C were modeled as sigmoidal Boltzmann curves, whereas the survival for temperatures 39-500C were modeled as the second-order exponential decay curves. The efficiency for cell inactivation was calculated as the light dose or exposure time required for 50% of cell survival, and it was found that the efficiency was higher at higher temperatures.