In this study, carboxymethyl sulfate derivative (CLBS) of locust bean gum (LBG) was synthesized by varying the strength of sulfating reagent. CLBS was characterized by Fourier transform infrared (FTIR) spectroscopy, elemental analysis, and viscosity measurements. Furthermore, the degree of sulfation and carboxymethylation in CLBS was determined. Novel micro(hydro)gel particles of CLBS were fabricated in basic aluminum chloride solution and different concentration of diclofenac sodium was incorporated into these particles. Differential scanning calorimetry and FTIR analyses did not suggest any drug-polymer interaction. Spherical morphological structures of the particles were evident under scanning electron microscope. Regardless of the formulation variables, a maximum of ~60% drug entrapment efficiency was achieved. For a higher degree of substitution, CLBS particles disintegrated rapidly (~20 min) and released >80% drug in acidic medium (pH1.2 and pH4.0) in 60 min. However, the particles liberated only ~60% drug in phosphate buffer medium (pH6.8) during this period. Following disintegration of the particles, the pH of gastric environment elevated. In stomach histopathology, the ulcers were scored and it was estimated that CLBS afforded ~86% protection to the gastric mucosa from ulceration. Thus, the micro(hydro)gel particles of CLBS-aluminium complex could be useful for immediate analgesic effect of the drug without any significant gastric distress.