Metal oxides with oxygen vacancies can be exploited as a charge storage material for supercapacitor. This work demonstrates synthesis of lanthanum molybdenum oxide (La2Mo2O9, LMO) using different calcination temperatures (300, 400, 500, 600 and 700 degrees C). As prepared LM0500 illustrates its utilization as an anion intercalated material for supercapacitors. Among all LMOs, LM0500 electrode exhibits high gravimetric (727.18 F g(-1) at 0.5 A g(-1) ) and areal (290.87 mF cm(-2) at 0.5 A g(-1)) capacitance. The superior electrochemical performance of LM0500 can be attributed to complete transformation of its mixed phases (i.e. oxides, hydroxides) to its pure oxides (beta-La-2 Mo2O9). Due to existence of pure phase, devoid of secondary phases, LM0500 exhibits good electron kinetics which affords low charge transfer resistance. The asymmetric supercapacitor (LMO500 parallel to LRGONR) employing lacey reduced graphene oxide nanoribbons (LRGONR) as negative electrode delivers high energy density of 52 Wh kg(-1) at a power density of 474 W kg(-1) which is more than twice of symmetric cell (LMO500 parallel to LM0500). Other than high energy and power density, LM0500 parallel to LGONR cell shows 98.74% capacitance retention after 1000 GCD cycles at 1.0 A g(-1), endorsing excellent cycle stability. (C) 2018 Elsevier Ltd. All rights reserved.