This report describes purification strategies, biochemical properties and thermodynamic analysis of an alkaline serine protease from a marine actinomycete, Nocardiopsis dassonvillei strain OK-18. The solvent tolerance, broad thermal-pH stability, favourable kinetics and thermodynamics suggest stability of the enzymatic reaction. The enzyme was active in the range of pH 7–12 and 37–90 °C, optimally at pH 9 and 70 °C. The deactivation rate constant (Kd), half-life (t½), enthalpy (ΔH*), entropy (ΔS*), activation energy (E) and change in free energy (ΔG*) suggested stability and spontaneity of the reaction. β-Sheets as revealed by the Circular dichroism (CD) spectroscopy, were the major elements in the secondary structure of the enzyme, while Fourier-transform infrared spectroscopy (FTIR) indicated the presence of amide I and amide II. Based on the liquid chromatography quadrupole time-of-flight mass spectrometry (LC-QToF-MS) analysis, the amino acid sequence had only 38% similarity with other proteases of Nocardiopsis strains, suggesting its novelty. The Ramachandran Plot revealed the location of the amino acid residues in the most favored region. The blood de-staining, gelatin hydrolysis, silver recovery and deproteinization of crab shells established the biotechnological potential of the enzyme. Display omitted •Cost-effective single-step purification•Thermodynamic, biochemical and structural elucidation of the protease•High enzyme stability in organic solvents, metal ions and other agents•Highly efficient in crab shell deproteinization, gelatin hydrolysis and silver recovery from used X-ray film•Highly compatible as a detergent supplement