BACKGROUND AND AIMS: Chemotherapy is one of the treatments of choice for patients with hematological or head and neck neoplasms. However, chemotherapy promotes elevate occurrence of adverse events and many of them directly impact nutritional status and patients' quality of life, which may include a low treatment tolerance. Suggested mechanisms include inflammation and oxidative stress as contributing factors to adverse effects of chemotherapy. Recently, we developed an adapted ice cream, source of protein and fiber, fat lower content, free of trans fat, gluten and lactose, one of the foods that are best accepted during chemotherapy, which have the potential of protein, cryotherapeutic and with the potential to alleviate gastrointestinal effects. The aim of this study is to develop a two-phase randomized clinical trial protocol. In this trial, the intake of an adapted ice cream will be tested during chemotherapy in adults of both sexes, with a recent diagnosis of hematological or head and neck cancer, with an indication to start chemotherapy, and who are able to take oral intake. METHODS: The study will be divided into two phases, with different intervention times. The adapted ice cream will be offered daily two 60 g plastic packaging (total 120 g/day), as a dessert for lunch and dinner for 21 days in phase 1 or 63-days post day one of chemotherapy in phase 2. Participants will be randomized by stratified randomization into the control (n = 26) and intervention (n = 26) groups. The primary outcomes are nutritional status and the incidence, duration, and severity of oral mucositis. Secondary outcomes are food consumption, inflammatory and oxidative stress indicators, taste disorders, and quality of life. DISCUSSION: Understanding the effect of this nutritional intervention on the outcomes we intend to analyze in this population may provide relevant information to assist with nutritional approaches during treatment. In this protocol, the methods for data collection are well based on the literature and have good validity for this population. The results of this study, whether positive or negative, will contribute to the clear scientific gap demonstrated in recent systematic reviews involving this topic. REGISTRATION NUMBER: RBR-5dvnbqx in ensaiosclinicos.gov.br.