This invention provides a process of preparation of novel polymorphic hemifumarate salts of 8-chloro-6,11-dihydro-11-(4-piperidylidene)-5H-benzo5,6-cyclohepta1,2-bpyridine, hereinafter called 'desloratadine'. These polymorphic salt forms show much higher solubility in water and also in protic organic solvents compare to the parent desloratadine. The process of preparing the polymorphic forms comprising: a) mixing the ethanolic solution of desloratadine and fumaric acid at a temperature of from about 55°C to 70°C, and stirring for 30 to 45 minutes after mixing, and thereafter filtering the solid thereby prepared in hot condition; to yield the polymorphic form 2 having a DSC of 232°C ± 2°C; or b) mixing the ethanolic solution of desloratadine and fumaric acid at a temperature of from about 15°C to room temperature (25°C) and stirring at this temperature for 30 to 45 minutes, then filtering at room temperature; to yield the polymorphic form 1 having a DSC of 224°C ± 2°C.