The effect of almost low concentrations of alumina hydrophilic (bare surface) and hydrophobic (modified surface with hexadecanoic acid) nanoparticles on interfacial tension of methylbenzene (toluene)-water was investigated based on experimental results from drop weight tensiometry. Nanoparticles were suspended in either aqueous or organic phases to provide a stable nanofluid and then were contacted with another phase to measure the interfacial tension. A nanoparticle mass fraction range of 1.10(-5) to 5.10(-4) (+/-5.10(-6)) and a temperature range of [293.2 to 323.2 (+/-0.1)] K were used. Interesting trends of interfacial tension variation were revealed with nanoparticles concentration, showing a sharp increase up to 55.7 mN.m(-1) (+/-0.1 mN.m(-1)) at 293.2 K, and a decrease to about 14.0 mN.m(-1) at 323.2 K with hydrophilic and hydrophobic forms, respectively. The effect of increasing temperature was found to reduce interfacial tension within the used ranges and significantly higher with hydrophilic nanoparticles.