A novel series of pyrazoline and thiazole derivatives incorporating 2-pyrazolin-5-one moiety were synthesized starting from α,β-unsaturated ketones under the effect of hydrazine derivatives and thiosemicarbazide. The obtained pyrazolines 4a, 4b were treated with different reagents to afford N-substituted pyrazolines 5a, 5b, 6a, 6b, 7a, 7b, 8a, 8b. N-Thiocarbamoyl pyrazolines 12a, 12b were cyclized using phenacyl bromide, 2,3-dichloroquinoxaline, and monochloroacetic acid afforded the novel pyrazolinyl thiazoles 13a, 13b, 14a, 14b, 15a, 15b, 16a, 16b, 16c, 16d, 16e, 16f. The newly synthesized compounds were characterized by analytical and spectral data.