The present article reports the preparation and characterization of polypropylene (PP) composite with pulque (Agave cantala) leaf fibres treated with sodium hydroxide or sodium chlorite. PP composite material of untreated fibres was also prepared for comparison. The composite samples prepared by hot press-moulding machine were analyzed using Fourier transform infrared, scanning electron microscopy (SEM), thermogravimetric analysis and tensile mechanical tests. SEM analysis pointed out that in the case of PP composite with alkali-treated fibre (AF), the multi-cellular nature of fibre filament appeared more clearly, and the fibre surface became rough as compared to other composite systems that may be the cause of better interlocking between PP matrix and fibres. Consequently, the PP composite with AF (i.e. PP/AF 80/20) exhibited higher values of elastic modulus than other composite systems. The composite of PP with alkali-treated pulque fibres also displayed higher thermal resistance than the composite of PP with raw or bleached fibres.