Natural plant fibre was loosened from ArchontophoenixAlexandrae ?King palm? leaf stalk by saltwater retting and washing, then sun-dried for 2 weeks. The fibre was pulverized and treated with 4 M sodium hydroxide (NaOH) for 30 minutes before washing to neutralize the fibre and sun dried. The pulverized treated and untreated King palm fibre was conditioned at oven-dry weight after 70 minutes of heating in the oven at a temperature of 50 ?C, before introducing them into the epoxy resin for the composites casting at various weight fractions of 0.028 weight of fibre per weight of epoxy resin (w/w), 0.056 w/w, 0.084 w/w and 0.112 w/w. The epoxy composites were suddenly pulled 10 m/min using the Testometric Universal Testing machine. The consequences of sudden pull on the reinforced epoxy matrix were noted. Mean values of force at break, stress at break, elongation at break, ultimate stress, and Young?s modulus were obtained for epoxy composites reinforced with treated and untreated King palm staple fibre. Results show that increased weight fraction of the treated King palm fibre in epoxy resin increased the mean force at break from 150.75 N for the unreinforced epoxy resin to 424.07 N for the reinforced epoxy resin and mean Young?s modulus from 404.82 Nm-2 for the unreinforced epoxy to 1088.7 Nm-2 and 1906 Nm-2 for the treated and untreated King palm fibre reinforced epoxy composites respectively. The mean ultimate stress, mean stress at break and mean yield point at break were also higher with increased weight fraction of the reinforcement from 0.028 to 0.112 in both cases of treated and untreated King palm fibre reinforced epoxy composites. However, the mean elongation at break, reduced from 4.233 mm for the unreinforced epoxy to 1.5173 mm and 3.3267 mm respectively for the treated and untreated King palm fibre reinforced epoxy composites. All the composites exhibited a pre-tensioning period, while increase in the weight fraction of the King palm fibre increased brittleness of the epoxy composites.