Abstract: The invention relates to a process of making ammonia gas indicator, using single wall carbon nanotubes (SWCNTs)/alumina (Al2O3) composite thick film, comprising the steps of (a) preparing a nanoporous SWCNTs/Al2O3 composite thick film of thickness in the range of 60 to 65?m prepared by sol-gel process; (b) curing the film at a temperature in the range of 450° C. to 500° C. for a time period in the range 0.5 to 2 hour to obtain a cured sample; (c) providing thick film planar electrodes of Ag—Pd paste on same side of the cured sample by screen printing; and (d) heat treating the resultant cured sample with electrodes at a temperature in the range of 800° C. to 850° C. for a time period in the range of 0.5 to 2 hours to obtain a gas indicator.