The effects of different temperature (15, 25, 30°C and glasshouse control) and moisture (75% FC, 60% FC and 45% FC) treatments at three growth stages (stage-I: vegetative to beginning of tuberization, stage-II: tuberization to initial tuber enlargement and stage-III: tuber enlargement to maturity) on net photosynthesis (PN), stomatal resistance (RS), transpiration rate (TR), dark respiration (DR) and leaf chlorophyll (SPAD value) were studied in several potatoes (Solanum tuberosum L. cvs. May Queen, Dejima and Normn 1) in pot experiments. Temperature at 25°C increased PN at all growth stages whereas 30°C treatment decreased the PN at all stages of growth. However, a decrease in RS and increase in DR, TR and leaf chlorophyll (LC) were observed under high temperature conditions. Similarly higher moisture (75% FC) increased the PN at all growth stages. But lower moisture decreased the DR, TR and increased the RS and LC. On total average, 17 and 37% PN, 18 and 37% TR, 26 and 41% DR decreased with the decrease of moisture level 60% FC and 45% FC respectively, over control (75% FC) . In the temperature treatments, 16% PN decreased by 30°C treatments, and 4 and 13% PN increased by 15 and 25°C temperature over control. Twenty percent TR and 35% DR increased by high temperature (30°C) treatments. PN decreased maximum at stage-II in temperature and stage-I in moisture treatment. From this study it can be concluded that moisture stress decreased more in the PN than that of temperature and leaf PN, RS, TR, DR, and LC are moisture as well as temperature dependent properties, and temperature 25°C is optimum for potato PN.