Penelitian bertujuan untuk menentukan formula dan karakter tiwul instan terbaik yang dibuat dari tepung mocaf dengan substitusi tepung koro pedang dan susu skim. Rancangan penelitian menggunakan rancangan acak kelompok. Faktor perlakuan terdiri dari proporsi tepung ubi kayu : tepung koro pedang : susu skim (P ; b/b) P1 = 80 : 15 : 5, P2 = 70 : 25 : 5, P3 = 60 : 35 : 5 dan modifikasi tepung ubi kayu (A) yaitu A0 = tanpa modifikasi dan A1 = modifikasi dengan ragi tape. Variabel yang dianalisis adalah sifat fisikokimia (kadar air, kadar abu, kadar lemak, kadar protein dan koefisien rehidrasi) dan sifat sensori (tekstur, rasa kacang, flavor dan kesukaan) yang diujikan kepada 25 panelis semi terlatih. Data dianalisis dengan Uji F (anova) dan dilanjutkan dengan DMRT (Duncan Multiple Range Test). Perlakuan terbaik berdasarkan uji indeks efektifitas adalah P3A0 (tepung ubi kayu-tepung koro pedang-susu skim 60 : 35 : 5, tanpa modifikasi) memiliki kandungan protein 8,84 %bk; lemak 1,66 %bk; air 6,68 %bb; abu 1,89 %bk dan koefisien rehidrasi 3,44. Hasil uji hedonic adalah tekstur 2,2 (agak kenyal); rasa kacang 2,9 (agak terasa); flavor 2,6 (agak enak) dan kesukaan 2,4 (agak disukai). To determine the best formula and character of instant tiwul made by mocaf flour subtituted with jack bean flour and skimmed milk, we conducted a factorial randomized design experiment. Treatments factors consist of proportion of cassava flour-jack bean flour-skimmed milk (P;w/w): P1 = 80 : 15 : 5, P2 = 70 : 25 : 5, P3 = 60 : 35 : 5 and type of cassava flour modification of (A): A0 = unmodified cassava flour, A1 = yeast modified cassava flour. Analyzed variables were 1) phsycochemical properties (water content, ash content, total fat, total protein, rehydration coefficient) and 2) sensory properties. Hedonic test were conducted to determine the level of consumer acceptance of 25 semi-trained panelists. Data were analyzed by F-test and Duncan's Multiple Range Test (DMRT). The best treatment combination in this study was P3A0 ( cassava flour-jack bean flour-skimmed milk 60 : 35 : 5, unmodified cassava flour). Instant tiwul P3A0 has 8.84% (dry basis/db) protein content, 1.66%db fat content, 6.68%wb water content, 1.89%db ash content, and 3.44 rehydration coefficient. The hedonic test values were texture 2.2 (somewhat chewy), bean taste 2.9 (rather noticeably), flavor 2.6 (rather good), and preference 2.4 (slightly favored).