It is shown that receptacle tissue of the rose of sharon can serve as an effective biocatalyst by the construction of a potentiometric membrane electrode with response and selectivity for arginine. Electrodes using this tissue in conjunction with $NH_3$ gas sensing probes yield good response to arginine in $10^{-1}M to 10^{-3}M$ range and retain activity for a least 1 weeks. The arginine-selective membrane electrode using tissue slices of the rose of sharon have good selectivity in presence of other amino acids. The optimum conditions are pH 8.0, $25^{circ}C$ and $20 {mu}m$ thickness of slices in 0.1 M phosphate buffer solution and $K_m$ values is $6.4 { imes} 10^{-6}(M)$.