The discharge in sugar solution occurred in three different phases: pre-discharge, the initiation and the formation of discharge, whereas the discharge in benzene happened in two main steps: pre-discharging and the formation of discharge. From the optical emission spectrum, the major active species obtained from sugar solution were Hα (656 nm), followed by atomic O (777 nm), H (486 nm) and relatively low intensity of atomic C (247 nm). For benzene and toluene solutions, the majority active species were observed to be C2 (513 nm) and CH (431 nm) and followed by Hα (656 nm). The results indicated pure benzene might be suitable solution applied for the synthesis of carbon nanoparticles in solution plasma process.